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();
}