I would hold off on the BIOS update, unless necessary.
It sounds like the audio was working before, so the current BIOS version should be fine with the onboard audio. The reason I say to hold off on the BIOS update, is because a bad BIOS flash can turn your motherboard into a paper weight.
What OS is on the system now? When it failed, what messages did you see?
Run the BIOS update, then the chipset drivers, then the audio drivers.
OS XP PRO SP3
after install...no messages ..just choise to restart..and after restart,,still audio driver not istall at device manager..can u tell me the step start install driver for this pc...