private void button1_Click(object sender, EventArgs e) { string Login = textUsername.Text.Trim(); string Pass = txtPassword.Text.Trim(); if (Login != "admin" || Pass != "123") { MessageBox.Show("Please enter correct username or pass", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information); return; } Aptek ZeferanAptek = new Aptek("Zeferan"); Medicine medicine = new Medicine(this, ZeferanAptek); medicine.Show(); medicine.dataGridView1.DataSource = ZeferanAptek.GetDerman(); medicine.comboBox1.DataSource = ZeferanAptek.GetDerman(); this.Hide(); }