Function keys not working normally
So my kitten really loves to walk/lay on my (MacBook Air) key board and recently he pressed some buttons and now my "function" keys (I think) are no longer working normally. For example, I can't change the screen/keyboard brightness or volume using the regular keys. When I hit them they either perform different functions or it makes a sound. How do I change it back to normal?
MacBook Air, macOS High Sierra (10.13.3)