Trouble with loading sketch

My Windows crashed on Sunday and I managed to get that working but then I had trouble with my keyboard so I decided to start over and reload my latest sketch but not all of the keys worked so I tried a different sketch that had minor differences and now the keys that werent working before are working, but others arent and theyre all on the very bottom row where just the four keys are. Is there any way to go back to the last working setup? Like roll it back? What would cause the keys to switch like that?