Arduino Uno no longer being recognised or powered by USB from Windows 8

I was in the middle of working on a project and I plugged the board into my laptop via USB. Nothing happened, no W8 sound to indicate a USB device has been plugged in, no "ON" LED on the board and the "Serial Port" option in the IDE is greyed out. I have no idea what I could have done to cause this. Sorry about the lack of info, I'm really at a loss for words because it was working fine half an hour ago and now it just seems to be completely dead.

Is this something that can be fixed?