What? Of your Piano? Seriously, if your going to ask a question its better to give too much info than not enough. It's sort of like telling the Doctor "I have numbness" but not telling them where!

All right, since this is in the computer section I assume you mean PC or Laptop board. As far as I know there are only two ways a cat sitting on the right side keys could make them not work. One is static charge (cats have a tendency to create static) and the other is pee. The second one is probably a buy a new board issue and the first or static problem (which I don't think would just affect one side of the board) could be solved with a clothes drier static sheet wiping. If it's a Desktop keyboard consider buying a new one (there are some $10 - $20 ones out there) but if it's a laptop, it will have to be serviced unless your willing to swap out the keyboard part yourself, and it can be tricky just to get it out let alone back in.