I've got an Hp laptop

Question

I've got an Hp laptop with a keypad attached to the right of the keyboard and when I hit the "num lock" button some of the letters on the keyboard change to typing numbers, and the keypad types numbers as well. how do I change it so that with num lock on the keyboard will still type letters and the keypad will type numbers? I've tried function about every button on the keyboard and nothing is working.