Choose proprieties then events
Instead of using Key_press event you may use Key_down event. You can find this as belowEvent
after double clicking here it will automatically this code
private void textbox1_KeyDown(object sender, KeyEventArgs e)
{
}
Problem solved now use as you want.
private void textbox1_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show(" Enter pressed ");
}
}