private void btnReturn_Click(object sender, EventArgs e)
        {
            Giris ot = new Giris();

            ot.Show();
            this.Hide();
        }
        private void CagriEkrani_FormClosed(object sender, FormClosedEventArgs e)
        {
            timer_Güncel.Start();
            Giris giris = new Giris();

            giris.Show();
            this.Hide();
        }