Sounds like your driver got removed. Usually it is on a disc. Otherwise you need to download it. To find out what sound card you have, you can download
www.softpedia.com/get/System/System-Info/WinAudit.shtml
which will tell you what hardware you have. Then you can google for it like "yamaha yz999 driver download"
Sometimes the manufacturer will have it, other times they just make the chip and sell it.
Good luck, hope this helps
Daniel Zee
June 2007