Hi SUJAYS,

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

Using this article i have modified with DataSet.

Populate (Bind) TreeView from database in ASP.Net

HTML

<h3>Vehicle Details</h3>
<hr />
<asp:TreeView ID="TreeView1" runat="server" ImageSet="XPFileExplorer" NodeIndent="15">
    <HoverNodeStyle Font-Underline="True" ForeColor="#6666AA" />
    <NodeStyle Font-Names="Tahoma" Font-Size="8pt" ForeColor="Black" HorizontalPadding="2px"
        NodeSpacing="0px" VerticalPadding="2px"></NodeStyle>
    <ParentNodeStyle Font-Bold="False" />
    <SelectedNodeStyle BackColor="#B5B5B5" Font-Underline="False" HorizontalPadding="0px"
        VerticalPadding="0px" />
</asp:TreeView>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = this.GetData("SELECT Id, Name FROM VehicleTypes").Tables[0];
        this.PopulateTreeView(dt, 0, null);
    }
}

private void PopulateTreeView(DataTable dtParent, int parentId, TreeNode treeNode)
{
    foreach (DataRow row in dtParent.Rows)
    {
        TreeNode child = new TreeNode
        {
            Text = row["Name"].ToString(),
            Value = row["Id"].ToString()
        };
        if (parentId == 0)
        {
            TreeView1.Nodes.Add(child);
            DataTable dtChild = this.GetData("SELECT Id, Name FROM VehicleSubTypes WHERE VehicleTypeId = " + child.Value).Tables[0];
            PopulateTreeView(dtChild, int.Parse(child.Value), child);
        }
        else
        {
            treeNode.ChildNodes.Add(child);
        }
    }
}

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

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = Me.GetData("SELECT Id, Name FROM VehicleTypes").Tables(0)
        Me.PopulateTreeView(dt, 0, Nothing)
    End If
End Sub

Private Sub PopulateTreeView(dtParent As DataTable, parentId As Integer, treeNode As TreeNode)
    For Each row As DataRow In dtParent.Rows
        Dim child As New TreeNode() With { _
         .Text = row("Name").ToString(), _
         .Value = row("Id").ToString() _
        }
        If parentId = 0 Then
            TreeView1.Nodes.Add(child)
            Dim dtChild As DataTable = Me.GetData("SELECT Id, Name FROM VehicleSubTypes WHERE VehicleTypeId = " + child.Value).Tables(0)
            PopulateTreeView(dtChild, Integer.Parse(child.Value), child)
        Else
            treeNode.ChildNodes.Add(child)
        End If
    Next
End Sub

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

Screenshot