'no output audio device is installed' but sound plays

As above. It says this in the icon in the tray, yet i can play songs fine. The only thing is, it also has my speakers to record, and i can't change it to front mic. any ideas? it was working perfectly fine yesterday... sound is onboard and uses Via hd audiodeck.
thanks

If this just happened, use the System Restore function and restore the PC back to a date when it worked correctly. System Restore can be accessed from Start/Programs/Accessories/System Tools.