Why Isn't The Keyboard Working On My MacBook Pro?

I was using Xcode’s Interface Builder on my MacBook Pro, trying to type in data for a label that I had just inserted into a view (Just typing a name for a label, if you don’t understand that part), when I realized I couldn’t type anything in. I could delete it, but then I couldn’t type anything back. I opened Safari to come ask you flutherers, but I couldn’t type anything there either. Same story when I opened Opera.

After a restart, i tried opening interface builder again to see if it would work this time, just to repeat what i explained just then. So now, I’m asking Fluther on another computer while a virus scan is operating on the MacBook Pro.