private void button2_Click(object sender, EventArgs e)
        {
            this.Hide();
            menu mm = new menu();

            mm.Show();
        }
 private void authentification_KeyDown(object sender, KeyEventArgs e)
 {
     if (e.Control == true && e.KeyCode == Keys.C)
     {
         this.Hide();
         menu m = new menu();
         m.Show();
     }
 }
        private void button1_Click(object sender, EventArgs e)
        {
            SqlDataAdapter sda = new SqlDataAdapter("select count(*) from admin where login ='******' and password='******'", con);
            DataTable      dt  = new DataTable();

            sda.Fill(dt);
            if (dt.Rows[0][0].ToString() == "1")
            {
                this.Hide();
                menu mm = new menu();
                mm.Show();
            }
            else
            {
                MessageBox.Show("please enter correct username and password", "alert", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }