protected void btnagree_Click(object sender, EventArgs e)
 {
     if (txtoldpassword.Text == tk.matKhau && txtnewmatkhau2.Text == txtnewmatkhau.Text)
     {
         TaiKhoan tkn = new TaiKhoan();
         tkn.maTaiKhoan   = tk.maTaiKhoan;
         tkn.tenTaiKhoan  = tk.tenTaiKhoan;
         tkn.matKhau      = txtnewmatkhau.Text;
         tkn.loaiTaiKhoan = tk.loaiTaiKhoan;
         tkn.anh          = tk.anh;
         lblalert.Text    = tkc.editTaiKhoan(tkn);
         Session["tk"]    = tkn;
         //Response.Redirect("AccountDetailView.aspx");
     }
     else
     {
         lblalert.Text = "Sai mật khẩu";
     }
 }