Why did the plug receptical stop working?

Possibilities:

1. Circuit breaker tripped?
2. GFI tripped? Many bathroom recepticles are equipped with a ground fault interrrupt (GFI) to prevent electricutions in wet environments. They have a "reset" button on them - see if you have one of these types of recepticles and try pressing the reset. Sometimes several recepticles are powered through one GFI, so if the receptacle that isn't working is not a GFI, look around the bathroom and see if there's another that is - they may be connected. It's also possible that the GFI device is integrated into the circuit breaker at the fuse box, so check there as well.