I've been sitting here for hours trying to figure out why I had no sound..... no clue. Well I finally went on my manufacture's website of my computer and went to drivers and downloads. Click on browse all downloads and put my computer info in and the problem. It came up with all these downloads for sound and I know that sigma is in the system somewhere, so I downloaded it once but the system went down. Then i uninstalled it and reinstalled it again and finally it took and I have sound again. But you have to read what each driver is for first. I chose the high definition driver of sigma. What an obstacle this was. But my advice is to try the manufacturer's website, mine was gateway and very self explanitory too. I hope this helps someone.