X-fi pci express stop working

Probably a setting through the audio chipset or software, are you running windows 7? have a look at the output channel settings in the X-fi software and start playing around there.

^ +1

Did this happen after having headphones plugged in? It could be a damaged headphone jack and the soundcard not knowing the headphones have been unplugged.

+1^ seems a very logical explanation with that sound card you should be able to set another sound output port as your default stereo output port try change it to a different physical port on the sounds card and see if that makes any difference.

Uninstall the SoundBlaster in the Device Manager (DO NOT uninstall the Drivers) and then restart the PC and when Windows starts it should detect and reinstall the sound card. This may fix it.

If not, reinstall the Creative drivers (get the latest drivers from the Creative site). You should have the What You Hear (what SoundBlaster calls the "System Mixer") and the other missing recording devices.

Hey razor as far as i know he has already tried new driver software and that has not worked for him. "'Ive tried updating drivers but no luck. "