USB Ports

The USB ports on my Macbook have seemingly stopped working all of sudden. Has anybody else had this problem and if so, how do I fix it?

Both of them? Are you still under warranty? Are you plugging in mice/keyboards and they aren't working? Check the System Profiler to see if the devices are being detected. I would run the Apple Hardware Test to see if any errors come up as well.

If you're still under warranty, I would get Apple to look at it. Logic board could be bad.