Sound problems with my computer?

My computer runs windows Vista. After removing a trojan horse virus with Webroot Anti-spyware, my computer isn't getting any sound. There is no start up or log off noise. I can't hear sound from Youtube or a DVD. There's a "beep" when I shut down. And when I tried to use Adobe Soundbooth to record-it told me the driver didn't allow recording. I was ale to before. I've downloaded the lastest driver, but that didn't fix the problem. Neither did a full system virus scan, an restoring the system to a previous point. I need to get sound back on my computer.