private void btn_Submit_Click(object sender, EventArgs e)
        {
            if (tb_Username.Text == "a" && tb_Password.Text == "a")
            {
                MessageBox.Show("Login Successfull...!!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);

                frm_Add_Student_Info ASObj = new frm_Add_Student_Info();
                this.Hide();
                ASObj.Show();
            }
            else
            {
                MessageBox.Show("Invalid Username or Password..!!", "Failure", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
            tb_Username.Text    = "";
            tb_Password.Text    = "";
            tb_Password.Enabled = false;
            btn_Submit.Enabled  = false;
            tb_Username.Focus();
        }
 private void btn_Back_Click(object sender, EventArgs e)
 {
     frm_Add_Student_Info AObj = new frm_Add_Student_Info();
     this.Close();
     AObj.Show();
 }