Hi baswal07,

I am referring following article.

Multilevel (N Level) Nested GridView (GridView inside GridView) in ASP.Net with Paging 

And I have modified the code as per your requirement.

I made changes in ImageButton OnClick (Show_Hide_OrdersGrid) event handler.

I used FOR EACH loop which executed over all the GridView rows to hide all the GridView if LinkButton is clicked to open another GridView.

Show_Hide_OrdersGrid

protected void Show_Hide_OrdersGrid(object sender, EventArgs e)
{
    ImageButton imgShowHide = (sender as ImageButton);
    GridViewRow row = (imgShowHide.NamingContainer as GridViewRow);

    foreach (GridViewRow rowAll in gvCustomers.Rows)
    {
        ImageButton imgBtnAll = rowAll.FindControl("imgOrdersShow") as ImageButton;

        if (imgShowHide.CommandArgument == "Show")
        {
            //Hidding all the GridView if LinkButton Is clicked to open GridView.
            rowAll.FindControl("pnlOrders").Visible = false;
            imgBtnAll.ImageUrl = "~/images/plus.png";
            imgBtnAll.CommandArgument = "Show";
        }
    }

    if (imgShowHide.CommandArgument == "Show")
    {
        row.FindControl("pnlOrders").Visible = true;
        imgShowHide.CommandArgument = "Hide";
        imgShowHide.ImageUrl = "~/images/minus.png";
        string customerId = gvCustomers.DataKeys[row.RowIndex].Value.ToString();
        GridView gvOrders = row.FindControl("gvOrders") as GridView;
        this.BindOrders(customerId, gvOrders);
    }
    else
    {
        row.FindControl("pnlOrders").Visible = false;
        imgShowHide.CommandArgument = "Show";
        imgShowHide.ImageUrl = "~/images/plus.png";
    }
}

Here is the complete working sample. You can also download sample zip.

Database

Download and install Northwind Database

HTML

<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" CssClass="Grid"
    DataKeyNames="CustomerID">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:ImageButton ID="imgOrdersShow" runat="server" OnClick="Show_Hide_OrdersGrid"
                    ImageUrl="~/images/plus.png" CommandArgument="Show" />
                <asp:Panel ID="pnlOrders" runat="server" Visible="false" Style="position: relative">
                    <asp:GridView ID="gvOrders" runat="server" AutoGenerateColumns="false" PageSize="5"
                        AllowPaging="true" OnPageIndexChanging="OnOrdersGrid_PageIndexChanging" CssClass="ChildGrid"
                        DataKeyNames="OrderId">
                        <Columns>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:ImageButton ID="imgProductsShow" runat="server" OnClick="Show_Hide_ProductsGrid"
                                        ImageUrl="~/images/plus.png" CommandArgument="Show" />
                                    <asp:Panel ID="pnlProducts" runat="server" Visible="false" Style="position: relative">
                                        <asp:GridView ID="gvProducts" runat="server" AutoGenerateColumns="false" PageSize="2"
                                            AllowPaging="true" OnPageIndexChanging="OnProductsGrid_PageIndexChanging" CssClass="Nested_ChildGrid">
                                            <Columns>
                                                <asp:BoundField ItemStyle-Width="150px" DataField="ProductId" HeaderText="Product Id" />
                                                <asp:BoundField ItemStyle-Width="150px" DataField="ProductName" HeaderText="Product Name" />
                                            </Columns>
                                        </asp:GridView>
                                    </asp:Panel>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:BoundField ItemStyle-Width="150px" DataField="OrderId" HeaderText="Order Id" />
                            <asp:BoundField ItemStyle-Width="150px" DataField="OrderDate" HeaderText="Date" />
                        </Columns>
                    </asp:GridView>
                </asp:Panel>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField ItemStyle-Width="150px" DataField="ContactName" HeaderText="Contact Name" />
        <asp:BoundField ItemStyle-Width="150px" DataField="City" HeaderText="City" />
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

VB.Net

Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        gvCustomers.DataSource = this.GetData("SELECT TOP 10 * FROM Customers");
        gvCustomers.DataBind();
    }
}

private DataTable GetData(string query)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = query;
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataSet ds = new DataSet())
                {
                    DataTable dt = new DataTable();
                    sda.Fill(dt);
                    return dt;
                }
            }
        }
    }
}

protected void Show_Hide_OrdersGrid(object sender, EventArgs e)
{
    ImageButton imgShowHide = (sender as ImageButton);
    GridViewRow row = (imgShowHide.NamingContainer as GridViewRow);

    foreach (GridViewRow rowAll in gvCustomers.Rows)
    {
        ImageButton imgBtnAll = rowAll.FindControl("imgOrdersShow") as ImageButton;

        if (imgShowHide.CommandArgument == "Show")
        {
            //Hidding all the GridView if LinkButton is clicked to open GridView.
            rowAll.FindControl("pnlOrders").Visible = false;
            imgBtnAll.ImageUrl = "~/images/plus.png";
            imgBtnAll.CommandArgument = "Show";
        }
    }

    if (imgShowHide.CommandArgument == "Show")
    {
        row.FindControl("pnlOrders").Visible = true;
        imgShowHide.CommandArgument = "Hide";
        imgShowHide.ImageUrl = "~/images/minus.png";
        string customerId = gvCustomers.DataKeys[row.RowIndex].Value.ToString();
        GridView gvOrders = row.FindControl("gvOrders") as GridView;
        this.BindOrders(customerId, gvOrders);
    }
    else
    {
        row.FindControl("pnlOrders").Visible = false;
        imgShowHide.CommandArgument = "Show";
        imgShowHide.ImageUrl = "~/images/plus.png";
    }
}

private void BindOrders(string customerId, GridView gvOrders)
{
    gvOrders.ToolTip = customerId;
    gvOrders.DataSource = this.GetData(string.Format("SELECT * FROM Orders WHERE CustomerId='{0}'", customerId));
    gvOrders.DataBind();
}

protected void OnOrdersGrid_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    GridView gvOrders = (sender as GridView);
    gvOrders.PageIndex = e.NewPageIndex;
    this.BindOrders(gvOrders.ToolTip, gvOrders);
}

protected void Show_Hide_ProductsGrid(object sender, EventArgs e)
{
    ImageButton imgShowHide = (sender as ImageButton);
    GridViewRow row = (imgShowHide.NamingContainer as GridViewRow);
    if (imgShowHide.CommandArgument == "Show")
    {
        row.FindControl("pnlProducts").Visible = true;
        imgShowHide.CommandArgument = "Hide";
        imgShowHide.ImageUrl = "~/images/minus.png";
        int orderId = Convert.ToInt32((row.NamingContainer as GridView).DataKeys[row.RowIndex].Value);
        GridView gvProducts = row.FindControl("gvProducts") as GridView;
        this.BindProducts(orderId, gvProducts);
    }
    else
    {
        row.FindControl("pnlProducts").Visible = false;
        imgShowHide.CommandArgument = "Show";
        imgShowHide.ImageUrl = "~/images/plus.png";
    }
}

private void BindProducts(int orderId, GridView gvProducts)
{
    gvProducts.ToolTip = orderId.ToString();
    gvProducts.DataSource = this.GetData(string.Format("SELECT ProductId, ProductName FROM Products WHERE ProductId IN (SELECT ProductId FROM [Order Details] WHERE OrderId = '{0}')", orderId));
    gvProducts.DataBind();
}

protected void OnProductsGrid_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    GridView gvProducts = (sender as GridView);
    gvProducts.PageIndex = e.NewPageIndex;
    this.BindProducts(int.Parse(gvProducts.ToolTip), gvProducts);
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        gvCustomers.DataSource = Me.GetData("SELECT TOP 10 * FROM Customers")
        gvCustomers.DataBind()
    End If
End Sub

Private Function GetData(query As String) As DataTable
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As New SqlConnection(constr)
        Using cmd As New SqlCommand()
            cmd.CommandText = query
            Using sda As New SqlDataAdapter()
                cmd.Connection = con
                sda.SelectCommand = cmd
                Using ds As New DataSet()
                    Dim dt As New DataTable()
                    sda.Fill(dt)
                    Return dt
                End Using
            End Using
        End Using
    End Using
End Function

Protected Sub Show_Hide_OrdersGrid(ByVal sender As Object, ByVal e As EventArgs)
    Dim imgShowHide As ImageButton = (TryCast(sender, ImageButton))
    Dim row As GridViewRow = (TryCast(imgShowHide.NamingContainer, GridViewRow))

    For Each rowAll As GridViewRow In gvCustomers.Rows
        Dim imgBtnAll As ImageButton = TryCast(rowAll.FindControl("imgOrdersShow"), ImageButton)

        If imgShowHide.CommandArgument = "Show" Then
            'Hidding all the GridView if LinkButton Is clicked to open GridView.
            rowAll.FindControl("pnlOrders").Visible = False
            imgBtnAll.ImageUrl = "~/images/plus.png"
            imgBtnAll.CommandArgument = "Show"
        End If
    Next

    If imgShowHide.CommandArgument = "Show" Then
        row.FindControl("pnlOrders").Visible = True
        imgShowHide.CommandArgument = "Hide"
        imgShowHide.ImageUrl = "~/images/minus.png"
        Dim customerId As String = gvCustomers.DataKeys(row.RowIndex).Value.ToString()
        Dim gvOrders As GridView = TryCast(row.FindControl("gvOrders"), GridView)
        Me.BindOrders(customerId, gvOrders)
    Else
        row.FindControl("pnlOrders").Visible = False
        imgShowHide.CommandArgument = "Show"
        imgShowHide.ImageUrl = "~/images/plus.png"
    End If
End Sub

Private Sub BindOrders(customerId As String, gvOrders As GridView)
    gvOrders.ToolTip = customerId
    gvOrders.DataSource = Me.GetData(String.Format("SELECT * FROM Orders WHERE CustomerId='{0}'", customerId))
    gvOrders.DataBind()
End Sub

Protected Sub OnOrdersGrid_PageIndexChanging(sender As Object, e As GridViewPageEventArgs)
    Dim gvOrders As GridView = TryCast(sender, GridView)
    gvOrders.PageIndex = e.NewPageIndex
    Me.BindOrders(gvOrders.ToolTip, gvOrders)
End Sub

Protected Sub Show_Hide_ProductsGrid(sender As Object, e As EventArgs)
    Dim imgShowHide As ImageButton = TryCast(sender, ImageButton)
    Dim row As GridViewRow = TryCast(imgShowHide.NamingContainer, GridViewRow)
    If imgShowHide.CommandArgument = "Show" Then
        row.FindControl("pnlProducts").Visible = True
        imgShowHide.CommandArgument = "Hide"
        imgShowHide.ImageUrl = "~/images/minus.png"
        Dim orderId As Integer = Convert.ToInt32(TryCast(row.NamingContainer, GridView).DataKeys(row.RowIndex).Value)
        Dim gvProducts As GridView = TryCast(row.FindControl("gvProducts"), GridView)
        Me.BindProducts(orderId, gvProducts)
    Else
        row.FindControl("pnlProducts").Visible = False
        imgShowHide.CommandArgument = "Show"
        imgShowHide.ImageUrl = "~/images/plus.png"
    End If
End Sub

Private Sub BindProducts(orderId As Integer, gvProducts As GridView)
    gvProducts.ToolTip = orderId.ToString()
    gvProducts.DataSource = Me.GetData(String.Format("SELECT ProductId, ProductName FROM Products WHERE ProductId IN (SELECT ProductId FROM [Order Details] WHERE OrderId = '{0}')", orderId))
    gvProducts.DataBind()
End Sub

Protected Sub OnProductsGrid_PageIndexChanging(sender As Object, e As GridViewPageEventArgs)
    Dim gvProducts As GridView = TryCast(sender, GridView)
    gvProducts.PageIndex = e.NewPageIndex
    Me.BindProducts(Integer.Parse(gvProducts.ToolTip), gvProducts)
End Sub

Screenshot