Originally Posted by
Perito
Get into Device Manager (Click START | RUN enter "devmgmt.msc" and click GO). Locate "Sound, video, and game controllers" Delete the entries that relate to the sound card. Click ACTION | Scan for hardware changes. The sound card should be found again. Use the "Automatic" (or whatever it says) for the install.
If that doesn't work (50:50 chance), try reinstalling your drivers from the original installation disks. If you don't have the original disks, you can download them from the card's manufacturer. In fact, getting the newest drivers for your card is probably better than installing from the original disks.
If you have any trouble, post back with more information.