How do I find Last active control

f you mean that you want to restore the input focus to whatever textbox had the input focus before the print button was pressed, then one thing you could do would be handle the Leave event of all textboxes (using the same handler for them all) and save a reference to the last one which had the focus in a private field on your form:

private TextBox lastTB = null;

private void textBox_Leave(object sender, System.EventArgs e)
{
   lastTB = (TextBox)sender;
}

// after saving form, restore focus to last TB which had input focus

if(lastTB != null) lastTB.Focus();