Matter of fact, this has happened to me before--with the exception that I know exactly what happened to kill the sound. (I fell asleep with my headphones on once, twitched in my sleep, and sent the whole rig careening to the floor--the headphone jack got jammed and subsequently destroyed. I'm much more careful now about not falling asleep with my lappy still on top of me.)

The solution was to buy an external sound drive that you plug into the USB port. You'd have to use headphones or external speakers with it, but it worked well enough. But I do hope you don't have to resort to something like that.