I would rather get a virus than facing Windows sound problem! It is a complex of settings and you cannot spot the problem easily. Recently my laptop had the same problem and after some hours of trying, i figured out that the speaker died all of a sudden. I would suggest you to reinstall the sound drivers and go to device manager and see if the device is recognized. If it is, go and check if speakers work. If they still dont work, it would be either a little setting in the labyrinth of windows sound settings (I doubt), or a broken speaker.
Good luck and dont forget to let me know!
cheers