Hi micah,

Check this example. Now please take its reference and correct your code.

HTML

<asp:DataList ID="dlCustomers" runat="server">
    <HeaderTemplate>
        <table>
            <tr>
                <th>Id</th>
                <th>Name</th>
                <th>Country</th>
                <th></th>
                <th></th>
            </tr>
    </HeaderTemplate>
    <ItemTemplate>
        <tr>
            <td><asp:Label ID="lblId" Text='<%#Eval("Id") %>' runat="server" /></td>
            <td><asp:Label ID="lblName" Text='<%#Eval("Name") %>' runat="server" /></td>
            <td><asp:Label ID="lblCountry" Text='<%#Eval("Country") %>' runat="server" /></td>
            <td><asp:LinkButton ID="lnkEdit" runat="server" Text="Edit" OnClick="OnEdit" /></td>
            <td>
                <asp:LinkButton ID="lnkDelete" runat="server" Text="Delete" OnClick="OnDelete"
                    OnClientClick="return confirm('Are you sure?')"/>
            </td>
        </tr>
    </ItemTemplate>
    <EditItemTemplate>
        <tr>
            <td><asp:Label ID="lblId" Text='<%#Eval("Id") %>' runat="server" /></td>
            <td><asp:TextBox ID="txtName" runat="server" Width="120" Text='<%# Eval("Name") %>' /></td>
            <td><asp:TextBox ID="txtCountry" runat="server" Width="120" Text='<%# Eval("Country") %>' /></td>
            <td><asp:LinkButton ID="lnkUpdate" runat="server" Text="Update" OnClick="OnUpdate" /></td>
            <td><asp:LinkButton ID="lnkCancel" runat="server" Text="Cancel" OnClick="OnCancel" /></td>
        </tr>
    </EditItemTemplate>
    <FooterTemplate>
        </table>
    </FooterTemplate>
</asp:DataList>

Namespaces

C#

using System.Data

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3]
        {
            new DataColumn("Id"),
            new DataColumn("Name"),
            new DataColumn("Country")
        });
        dt.Rows.Add(1, "John Hammond", "United States");
        dt.Rows.Add(2, "Mudassar Khan", "India");
        dt.Rows.Add(3, "Suzanne Mathews", "France");
        dt.Rows.Add(4, "Robert Schidner", "Russia");
        ViewState["Customers"] = dt;
        this.BindDatalist();
    }
}
protected void OnDelete(object sender, EventArgs e)
{
    DataListItem item = (sender as LinkButton).NamingContainer as DataListItem;
    DataTable dt = ViewState["Customers"] as DataTable;
    dt.Rows[item.ItemIndex].Delete();
    ViewState["Customers"] = dt;
    this.BindDatalist();
}
protected void OnEdit(object sender, EventArgs e)
{
    DataListItem item = (sender as LinkButton).NamingContainer as DataListItem;
    dlCustomers.EditItemIndex = item.ItemIndex;
    this.BindDatalist();
}

protected void OnUpdate(object sender, EventArgs e)
{
    DataListItem item = (sender as LinkButton).NamingContainer as DataListItem;
    DataTable dt = (DataTable)ViewState["Customers"];
    string country = (item.FindControl("txtCountry") as TextBox).Text;
    string CustomerName = (item.FindControl("txtCustomerName") as TextBox).Text;
    dt.Rows[item.ItemIndex]["CustomerName"] = CustomerName;
    dt.Rows[item.ItemIndex]["Country"] = country;
    ViewState["Customers"] = dt;
    dlCustomers.EditItemIndex = -1;
    this.BindDatalist();
}

protected void OnCancel(object sender, EventArgs e)
{
    dlCustomers.EditItemIndex = -1;
    this.BindDatalist();
}
private void BindDatalist()
{
    dlCustomers.DataSource = (DataTable)ViewState["Customers"];
    dlCustomers.DataBind();
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.AddRange(New DataColumn(2) { 
            New DataColumn("Id"), 
            New DataColumn("Name"), 
            New DataColumn("Country")})
        dt.Rows.Add(1, "John Hammond", "United States")
        dt.Rows.Add(2, "Mudassar Khan", "India")
        dt.Rows.Add(3, "Suzanne Mathews", "France")
        dt.Rows.Add(4, "Robert Schidner", "Russia")
        ViewState("Customers") = dt
        Me.BindDatalist()
    End If
End Sub

Protected Sub OnDelete(ByVal sender As Object, ByVal e As EventArgs)
    Dim item As DataListItem = TryCast((TryCast(sender, LinkButton)).NamingContainer, DataListItem)
    Dim dt As DataTable = TryCast(ViewState("Customers"), DataTable)
    dt.Rows(item.ItemIndex).Delete()
    ViewState("Customers") = dt
    Me.BindDatalist()
End Sub

Protected Sub OnEdit(ByVal sender As Object, ByVal e As EventArgs)
    Dim item As DataListItem = TryCast((TryCast(sender, LinkButton)).NamingContainer, DataListItem)
    dlCustomers.EditItemIndex = item.ItemIndex
    Me.BindDatalist()
End Sub

Protected Sub OnUpdate(ByVal sender As Object, ByVal e As EventArgs)
    Dim item As DataListItem = TryCast((TryCast(sender, LinkButton)).NamingContainer, DataListItem)
    Dim dt As DataTable = CType(ViewState("Customers"), DataTable)
    Dim country As String = (TryCast(item.FindControl("txtCountry"), TextBox)).Text
    Dim CustomerName As String = (TryCast(item.FindControl("txtCustomerName"), TextBox)).Text
    dt.Rows(item.ItemIndex)("CustomerName") = CustomerName
    dt.Rows(item.ItemIndex)("Country") = country
    ViewState("Customers") = dt
    dlCustomers.EditItemIndex = -1
    Me.BindDatalist()
End Sub

Protected Sub OnCancel(ByVal sender As Object, ByVal e As EventArgs)
    dlCustomers.EditItemIndex = -1
    Me.BindDatalist()
End Sub

Private Sub BindDatalist()
    dlCustomers.DataSource = CType(ViewState("Customers"), DataTable)
    dlCustomers.DataBind()
End Sub

Screenshot