if the light is on then the power side should be ok.....speakers rarely (if ever) 'pop' at the same time, normally one will go before the other.
from the start:
make sure your sound has not been muted by another application, i had one game that used to do this every time i played then closed it down.
check your leads, not unusual to pull a lead out or loosen it while moving the pc or even the mouse/k/board.
if all leads check out then make sure the sound card is still seen as installed, also not unusual for a pc to 'lose' drivers.
worth removing and re-installing drivers just for the hell of it.
there is also a chance the card may have 'crept' out and need pushing back into place.
as with any other electrical component, there is a chance the sound card has died, although i have to say i have rarely had a card 'die' on me unless i have done something wrong.
ian, July 2008
