Sound problems are common. The fact that you had sound, lost it and "going back" didn't help may mean a motherboard problem. I'm assuming that you didn't go into CMOS and make any changes, etc. If uninstalling drivers, then letting it redetect them and reinstalling them looks like it works, but you still get No Audio Device error then you might want to take the easy way out. Buy an inexpensive Sound Card that will fit your computer. Make sure you have an available slot for it. Disable the old card in Setup (CMOS) (usually under integrated peripherals ) Follow instructions that come with new card and your sound should work fine. I just went through this for a friend. New card was under $10.00. Wasn't worth the time to try and track down what was going on. Up and working in 10 Min.