Webcam in Windows 7 upgrade

I have an HP Pavilion laptop with a built in webcam. A couple years ago when I bought it, it still had XP and when Windows 7 came out, they provided me with the software to upgrade. After the upgrade, my webcam stopped working. The computer doesn't recognize it at all. It just says I have no webcam installed. I've tried installing every driver out there, but nothing works. Anyone have any advice?
