Rear audio output doesn't work

[Newmaven]

I have speakers plugged into the rear audio jack of my PC and (usually) a headset plugged into the front mic and earphone jacks. When I unplug the headset, I get no sound from the speakers. I've verified that the speakers work fine from other sources, and the headset gets no sound when plugged into the rear output jack.

How do I diagnose and fix this?

 

[fireberd]

More system info is needed.

One possible problem is a front panel jack problem that the PC thinks a headset is still plugged in after its removed. To check that the front panel is not causing the problem, disconnect the front panel audio connection from the motherboard and see if that fixes it.