Hi Guys I have solved this by some one help !
protected void Page_Load(object sender, EventArgs e)
{
string userid = Request.Cookies["UserDetails"]["UserName"].ToString();
string pass = Request.Cookies["UserDetails"]["Password"].ToString();
Authenticate_User(new System.Web.UI.HtmlControls.HtmlInputText() {Value=userid }, new System.Web.UI.HtmlControls.HtmlInputText() {Value=pass });
};