Thanks for letting us know that you resolved your issue. An easy solution is often the best and can be a good lesson (even to techies like me)
For years I worked in IT support and it still makes me laugh how people get upset when we ask them "have you rebooted the computer". They think we are being lazy, but it's simply the first thing on many troubleshooting lists.
By the way in case your issue returns (or someone else stumbles across this and needs help):
1. Look for latest drivers on the manufacturers website (not MSupdate) download and install.
2. Check that all cables and speakers are ok.
3. Check that the sound card (if not onboard) is sitting in the slot correctly.