edit update multiple gridview row and cell values on a single click

Anyways i have found a solution for you

Page

<form id="form1" runat = "server">
      <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns = "False"
            Font-Names = "Arial">
            <Columns>
                <asp:TemplateField HeaderText = "Item">
                <ItemTemplate>
                    <asp:Label ID="lblItem" runat="server"  Text='<%#Eval("Item") %>'></asp:Label>
                    <asp:TextBox ID="txtItem" runat="server" Text='<%#Eval("Item") %>' Visible = "false"></asp:TextBox>
                </ItemTemplate>
                </asp:TemplateField>
                 <asp:TemplateField HeaderText = "Price">
                <ItemTemplate>
                    <asp:Label ID="lblPrice" runat="server" Text='<%#Eval("Price") %>'></asp:Label>
                    <asp:TextBox ID="txtPrice" runat="server" Text='<%#Eval("Price") %>' Visible = "false"></asp:TextBox>
                </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
    <asp:Button ID="btnEdit" runat="server" Text="Edit" OnClick = "Edit" />
    <asp:Button ID="btnUpdate" runat="server" Text="Update" OnClick = "Update" />
    </form>

Code

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[2] { new DataColumn("Item"), new DataColumn("Price") });
        dt.Rows.Add("Shirt", 200);
        dt.Rows.Add("Football", 30);
        dt.Rows.Add("Bat", 22.5);
        dt.Rows.Add("Ring", 25);
        dt.Rows.Add("Band", 77);
        dt.Rows.Add("Glass", 57);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }

}
protected void Edit(object sender, EventArgs e)
{
    foreach (GridViewRow row in GridView1.Rows)
    {
        if (row.RowType == DataControlRowType.DataRow)
        {
            row.FindControl("txtItem").Visible = true;
            row.FindControl("lblItem").Visible = false;
            row.FindControl("txtPrice").Visible = true;
            row.FindControl("lblPrice").Visible = false;
        }
    }
}
protected void Update(object sender, EventArgs e)
{
    foreach (GridViewRow row in GridView1.Rows)
    {
        if (row.RowType == DataControlRowType.DataRow)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                Label lblItem = (row.FindControl("lblItem") as Label);
                Label lblPrice = (row.FindControl("lblPrice") as Label);
                TextBox txtItem = (row.FindControl("txtItem") as TextBox);
                TextBox txtPrice = (row.FindControl("txtPrice") as TextBox);
                    
                lblItem.Visible = true;
                txtItem.Visible = false;
                lblPrice.Visible = true;
                txtPrice.Visible = false;

                lblItem.Text = txtItem.Text;
                lblPrice.Text = txtPrice.Text;

                string item = lblItem.Text;
                string price = lblPrice.Text;

                //Update database row here
            }
        }
    }
}

 Output

Edit Mode