Help! Laptop Says I Have No Audio Output

Hi, I own a Compaq Presario f700 (Vista) laptop that I have had since March of 2007. I have never had any problems with my laptop up until now. I had downloaded the Veoh (web) player, and DivX web player/player/converter/codec pack, and Google chrome about two to three months ago and suddenly decided I needed to clean up my computer since it would freeze or become laggy when I tried to watch a video. Google chrome one day said that the flash player has become inresponsive and asked me if I would like to end that, so I clicked yes and next thing I know.. my audio is no longer around.. I have a little red circle with a white x next to the speakers upon all of this happening I decided to get rid of all of those programs. After that, I tried going to the Device Manager.. but I can not find a sound driver, the only thing I can find is under System Devices, and that would be the System speaker. I tried uninstalling and updating. My sound came back one time, and while I was listening to music in iTunes, it began to become inresponsive and I once again lost my audio. I can not recall downloading anything but AIM at the time. Help!