Strumming won't work suddenly

I was playing just fine with a ps2 controller through an adapter for a couple or so hours so I closed the game and unplugged my controller to take a quick break and when I opened the game again, it wouldn't let me strum up. I tried using a different guitar and now it wont let me strum down. Anybody have an idea what's going on here?? It was running flawlessly before.