sound driver problems

Recently my friend and i have encountered problems with our computer in which resetting it was required. We both backed up our music for our zunes on discs and went from there. My friend spent his time ressetting and updating things, but since then our sound device has not been working. We know for sure that our speakers still work. i've already heard that we should update our sound driver but what other things can i try to make the sound work.

Also the message i get goes lke this" Your computer may not have a sound device or it might not be working correctly" Any suggestions??????