Does your PC have Integrated Sound, or do you have a robust Sound Card. If you are not sure, the integrated card is what comes standard from most large PC vendors, just your basic stuff.
The robust Sound Card, refers to either a third party component such as Sound Blaster......or one you might have chosen for better sound when you purchased the PC.
If you have a Driver CD that came with your PC, you may be able to reinstall it, that is if it is gone, or if you have an aftermarket sound card, it no doubt would also have it's own Drivers disk.
You might try to do a "System Restore", that is if you can remember the last time your PC was working properly. But, before that, you want to make sure that your free of any nasties that might be lurking on your machine. Things you should have
, and if not, get them-Here are some free, recommended Apps.: An Anti-Virus Program: AVG Anti-Virus A Firewall: ZoneAlarm Spyware/Adware/Malware/etc....: Adaware SE Spybot S & D SpywareBlaster SpywareGaurd Recommended readings: Using Spybot - Search & Destroy to remove Spyware from Your Computer Using Ad-Aware SE to remove Spyware & Hijackers from Your Computer Using SpywareBlaster to protect your computer from Spyware, Hijackers, and Malware Using SpywareGuard to protect your computer from Spyware/Hijackers
There are more out there that will advance your protection, but those above, would be a really great start. I recommend installing what you don't already have. e.g. a firewall,anti-virus...and so on.
Hope this helps,