Go to control panel, then switch it to classic view if its not already like that. Go to system, then hardware, then click on the button that says "device manager". There should be a list of all of your components. Click on Sound and Game controllers (on most computers) and then look at the list that drops down. Enable and disable all of them, and see if anything sprouts a red X or a yellow dot with a '!'. If it looks like its your sound card, then yeah, you probably fried it or something. Try enabling and re-installing the drivers, that might help. I once did that to my computer somehow, and reinstalling XP was the only way I found to fix it.
"What if the hokey pokey really is whats its all about?"