If they are damaged, they may need to be replaced, but also their is a way to do some sort of command promt and fix your buttons. check the control panel. Good luck
they probably need to be cleaned out or something, but i wouldnt mess with the physical aspects of it. just get into the new habit of pressing the Fn key (its the one on the lower left corner in blue) and look at the page up/down buttons (upper right corner) it works the same way but ive always found that way easier