Hi nauna,

Refer below sample.

HTML

<asp:ListView ID="ListView1" runat="server" OnItemCommand="ListView1_ItemCommand">
    <ItemTemplate>
        <div class="pickup">
            <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            <br />
            <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            <br />
            <asp:LinkButton ID="LinkButton2" runat="server" CommandName="Remove">Remove</asp:LinkButton><br />
        </div>
    </ItemTemplate>
</asp:ListView>
<asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" OnClick="ButtonAdd_Click" />
<asp:Button Text="Save" runat="server" OnClick="Button1_Click" />

Namespaces

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        SetInitialRow();
    }
}

protected void ListView1_ItemCommand(object sender, ListViewCommandEventArgs e)
{
    int rowID;
    if (e.Item.DataItemIndex == 0 || e.Item.DataItemIndex == ListView1.Items.Count - 1)
    {
        rowID = ListView1.Items[e.Item.DataItemIndex].DataItemIndex;
    }
    else
    {
        rowID = ListView1.Items[e.Item.DataItemIndex + 1].DataItemIndex;
    }
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        if (dt.Rows.Count > 1)
        {
            if (ListView1.SelectedIndex < dt.Rows.Count - 1)
            {
                dt.Rows.Remove(dt.Rows[rowID]);
            }
        }
        ViewState["CurrentTable"] = dt;
        ListView1.DataSource = dt;
        ListView1.DataBind();
    }

    SetPreviousData();
}

private void SetInitialRow()
{
    DataTable dt = new DataTable();
    DataRow dr = null;
    dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
    dt.Columns.Add(new DataColumn("Column1", typeof(string)));
    dt.Columns.Add(new DataColumn("Column2", typeof(string)));

    dr = dt.NewRow();
    dr["RowNumber"] = 1;
    dr["Column1"] = string.Empty;
    dr["Column2"] = string.Empty;
    dt.Rows.Add(dr);
    ViewState["CurrentTable"] = dt;
    ListView1.DataSource = dt;
    ListView1.DataBind();
}

private void AddNewRow()
{
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
        DataRow drCurrentRow = null;
        if (dtCurrentTable.Rows.Count > 0)
        {
            for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
            {
                TextBox box1 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox1");
                TextBox box2 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox2");
                drCurrentRow = dtCurrentTable.NewRow();
                drCurrentRow["RowNumber"] = i + 1;
                drCurrentRow["Column1"] = box1.Text;
                drCurrentRow["Column2"] = box2.Text;
                rowIndex++;
            }
            dtCurrentTable.Rows.Add(drCurrentRow);
            ViewState["CurrentTable"] = dtCurrentTable;

            ListView1.DataSource = dtCurrentTable;
            ListView1.DataBind();
        }
    }
    else
    {
        Response.Write("ViewState is null");
    }
    SetPreviousData();
}

private void SetPreviousData()
{
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        if (dt.Rows.Count > 0)
        {
            for (int i = 1; i < dt.Rows.Count; i++)
            {
                TextBox box1 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox1");
                TextBox box2 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox2");
                box1.Text = dt.Rows[i]["Column1"].ToString();
                box2.Text = dt.Rows[i]["Column2"].ToString();
                rowIndex++;
            }
        }
    }
}

protected void ButtonAdd_Click(object sender, EventArgs e)
{
    AddNewRow();
}
protected void Button1_Click(object sender, EventArgs e)
{
    string message = "";
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
        if (dtCurrentTable.Rows.Count > 0)
        {
            for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
            {
                TextBox box1 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox1");
                TextBox box2 = (TextBox)ListView1.Items[rowIndex].FindControl("TextBox2");
                rowIndex++;
                message += box1.Text + "," + box2.Text + "\\n\\r";
            }
            Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert('" + message + "');", true);
        }
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        SetInitialRow()
    End If
End Sub

Protected Sub ListView1_ItemCommand(ByVal sender As Object, ByVal e As ListViewCommandEventArgs)
    Dim rowID As Integer
    If e.Item.DataItemIndex = 0 OrElse e.Item.DataItemIndex = ListView1.Items.Count - 1 Then
        rowID = ListView1.Items(e.Item.DataItemIndex).DataItemIndex
    Else
        rowID = ListView1.Items(e.Item.DataItemIndex + 1).DataItemIndex
    End If

    If ViewState("CurrentTable") IsNot Nothing Then
        Dim dt As DataTable = CType(ViewState("CurrentTable"), DataTable)
        If dt.Rows.Count > 1 Then
            If ListView1.SelectedIndex < dt.Rows.Count - 1 Then
                dt.Rows.Remove(dt.Rows(rowID))
            End If
        End If

        ViewState("CurrentTable") = dt
        ListView1.DataSource = dt
        ListView1.DataBind()
    End If

    SetPreviousData()
End Sub

Private Sub SetInitialRow()
    Dim dt As DataTable = New DataTable()
    Dim dr As DataRow = Nothing
    dt.Columns.Add(New DataColumn("RowNumber", GetType(String)))
    dt.Columns.Add(New DataColumn("Column1", GetType(String)))
    dt.Columns.Add(New DataColumn("Column2", GetType(String)))
    dr = dt.NewRow()
    dr("RowNumber") = 1
    dr("Column1") = String.Empty
    dr("Column2") = String.Empty
    dt.Rows.Add(dr)
    ViewState("CurrentTable") = dt
    ListView1.DataSource = dt
    ListView1.DataBind()
End Sub

Private Sub AddNewRow()
    Dim rowIndex As Integer = 0

    If ViewState("CurrentTable") IsNot Nothing Then
        Dim dtCurrentTable As DataTable = CType(ViewState("CurrentTable"), DataTable)
        Dim drCurrentRow As DataRow = Nothing
        If dtCurrentTable.Rows.Count > 0 Then
            For i As Integer = 1 To dtCurrentTable.Rows.Count
                Dim box1 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox1"), TextBox)
                Dim box2 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox2"), TextBox)
                drCurrentRow = dtCurrentTable.NewRow()
                drCurrentRow("RowNumber") = i + 1
                drCurrentRow("Column1") = box1.Text
                drCurrentRow("Column2") = box2.Text
                rowIndex += 1
            Next

            dtCurrentTable.Rows.Add(drCurrentRow)
            ViewState("CurrentTable") = dtCurrentTable
            ListView1.DataSource = dtCurrentTable
            ListView1.DataBind()
        End If
    Else
        Response.Write("ViewState is null")
    End If

    SetPreviousData()
End Sub

Private Sub SetPreviousData()
    Dim rowIndex As Integer = 0

    If ViewState("CurrentTable") IsNot Nothing Then
        Dim dt As DataTable = CType(ViewState("CurrentTable"), DataTable)
        If dt.Rows.Count > 0 Then
            For i As Integer = 1 To dt.Rows.Count - 1
                Dim box1 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox1"), TextBox)
                Dim box2 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox2"), TextBox)
                box1.Text = dt.Rows(i)("Column1").ToString()
                box2.Text = dt.Rows(i)("Column2").ToString()
                rowIndex += 1
            Next
        End If
    End If
End Sub

Protected Sub ButtonAdd_Click(ByVal sender As Object, ByVal e As EventArgs)
    AddNewRow()
End Sub

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim message As String = ""
    Dim rowIndex As Integer = 0
    If ViewState("CurrentTable") IsNot Nothing Then
        Dim dtCurrentTable As DataTable = CType(ViewState("CurrentTable"), DataTable)
        If dtCurrentTable.Rows.Count > 0 Then
            For i As Integer = 1 To dtCurrentTable.Rows.Count
                Dim box1 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox1"), TextBox)
                Dim box2 As TextBox = CType(ListView1.Items(rowIndex).FindControl("TextBox2"), TextBox)
                rowIndex += 1
                message += box1.Text & "," + box2.Text & "\n\r"
            Next
            Page.ClientScript.RegisterClientScriptBlock(GetType(Page), "Script", "alert('" & message & "');", True)
        End If
    End If
End Sub

Screenshot