private void btnEnter_Click(object sender, EventArgs e) { if (!string.IsNullOrEmpty(txt_UserName.Text) && !string.IsNullOrEmpty(txtPassword.Text)) { userService userService = new userService(); user userControl = userService.userControl(txt_UserName.Text, txtPassword.Text); if (userControl != null) { Form mainForm = Application.OpenForms["Form1"]; Panel leftPanel = (Panel)mainForm.Controls["pnlIslemList"]; GroupBox grpIslemList = (GroupBox)leftPanel.Controls["grpOperationList"]; foreach (Control item in grpIslemList.Controls) { if (item is Button) { item.Enabled = true; } } MessageBox.Show("Welcome to TO DO...", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information); this.Close(); } else { MessageBox.Show("Wrong username or password", "Information", MessageBoxButtons.OK, MessageBoxIcon.Error); } } else { MessageBox.Show("Enter your user name or password.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Error); } }