USB ISSUE

Provided it's not a hardware issue (like broken cable, defective plug or even a defective USB on your motherboard etc)
You got to go through a process of elimination:
Take a hard look on what you've installed/updated/done since the cam worked last time.
Try the cam on a different computer to exclude it as the source, plug in some other USB device to see if the usb ports of the laptop are working OK
To exclude any recent software changes I would use a restore point from the time when the cam still worked. (if that doesn't help you could always revert this because Windows creates a new restore point before it uses a previously made one)

Good Luck

-DG