Perhaps a BIOS update?
Did you crash your computer?
If the audio controller is integrated onto the motherboard then the driver should be in the CD that came with your motherboard.
Most of the time this comes integrated. Try using Device Manager to Update your drivers, and select the appropriate Windows Generic drivers for the audio/video/multimedia controllers with "!" next to them.
Also, in your BIOS, for the Audio option, see what options does it give you instead of "Auto" or "Enabled".
Besides this, there is nothing else that I can think of. If the problem persists I suggest you burn your computer and buy a palm pilot?