Speakers/Sound system just stopped.

Hello,
My laptop's sound/speakers have stopped working. I was listening to a file on iTunes and it said it had detected a fault with the file and stopped. Since then I can't get the laptop to play any sounds through either the speakers or headphones.

I've checked the volume properties and the slider for PCspeakers is 'greyed-out' as though it thinks there aren't any installed. I've checked the audio and sound properties via control panel and it says that the sound sytem and pc speakers are enabled and they both have no faults detected.

It's as if something has turned off or disabled the audio systems.

Any ideas / help / miracles would be appreciated.

Laptop is a Toshiba....Operating system Windows XP