no audio device installed

I have a gateway notebook model mx 6920 with intel centrino. I upgraded from windows xp to vista home and now I have no sound and when I point mouse over speaker on tool bar it resds "no audio device installed". I tried un installing audio device in device manager and rebooted but no change. I also tried updating driver and it stated best drive driver already installed. Thanks in advance for any help.

 

Have you made any changes to BIOS lately-updated BIOS? You may want to make sure that onboard sound is enabled in BIOS or even restore optimized defaults.