ok.. my computer has stopped producing sound.

Windows seems to THINK it works... (no errors, everything is fine in the device manager) but its not.
The stereo is fine... everything seems to be working.

Except for the lack of sound.

I can't find anything wrong with the cables either.. and it WAS working until last night where.. while I was playing an internet radio.. its just stopped.
It seemed to coincide with my playing around with an MS voice pack thing (you know.. those text to speach things windows has) it just died then.

I can't seem to find anything wrong at all.. and suggestions