Working with Session Variables

List<string> txt = new List<string>();
protected void Button1_Click(object sender, EventArgs e)
{
    foreach (Control ctrl in form1.Controls)
    {
        if (ctrl is TextBox)
        {
            txt.Add(((TextBox)ctrl).Text);
            Session.Add("lst",txt);
        }
    }
}
protected void Button2_Click(object sender, EventArgs e)
{
  txt=(List<string>)  Session["lst"];
    GridView1.DataSource = txt.ToList();
    GridView1.DataBind();
}