On your Loginpage put this..Madhuuuuuuuuuuuuu
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));
Response.Cache.SetNoStore();
Response.Buffer = true;
Response.ExpiresAbsolute = DateTime.Now.AddDays(-1d);
Response.Expires = -1500;
Response.CacheControl = "";
if (Session["username"] == null)
{
Response.Redirect("../Login.aspx");
}
}