Excel right and left arrows not working properly

Hello,

I spilled Coke on my laptop this afternoon and while frantically trying to remove it I pressed something that has inserted some kind of preference and now using the right and left arrow keys is not allowing me to move cell to cell but instead it's either putting a '0' or trying to insert a subtraction formula (I think). How's that for a run-on sentence? Help!!!

Note: The arrow keys are working as normal in other programs. I have tried opening/closing Excel, rebooting computer.