1. Make sure your virus is actually gone. Go to http://www.grisoft.com/ and get the excellent and free AVG anti-virus software. Use this to make sure any bug that may have been there isn't there anymore.
2. Figure out what kind of sound-card you have. The sound card may be part of the motherboard. If you don't have the manuals for the computer anymore, go to the manufacturer's Web site and try to find out what it is. C-media is a popular on-motherboard sound chipset, for instance.
3. Once you find that, either try to find the drivers at your computer manufacturer's site (usually found in 'drivers' or 'technical support/downloads' or similar). If they aren't there either A) If it's an on-motherboard sound chip, go to the motherboard manufacturer's site and get the driver, or B) go to the Soundcard manufacturer's site, and get the driver. C) if you still can't find it, Google search "systemax sound card" or "sytemax sound driver" and see if you can't find it that way.
4. Once you download the driver, it will usually be in an installation-friendly format. Unzip it if it's zipped (by double-clicking it), and then double-click it to install. Apologies if that's obvious -- I don't know how savvy you are.
5. Once you've installed and re-booted, your sound should work.
6. Finally, if everything else has failed, go to the taskbar speaker-shaped icon and make sure the volume is up... i'm embarassed to say that this has flummoxed me more than once.
