I've been having a few USB devices going crazy lately (mostly memory sticks) where the system decides that they are 'unknown USB devices' and it seems to spoil the bus until I remove them. For things that you can unplug, try to do so (I doubt the camera can be 'unplugged') and see if things start working again (maybe after a reboot). If the camera is the only USB device... see if it works. And add things until things stop working.
If nothing works from the start, the USB controller or header might have an issue. This sounds like its a laptop, so it might have to go in for service. Check with the manufacturer there. Good luck!