Sound problems

[dwarfer]

My PC is in my houses front room where everyone watches TV and stuff so If I want to listen to music it has to be through headphones, which has never been a problem until recently. The front jack has started only outputting sound in mono as opposed to stereo, but if I plug the headphones into the back of the pc it all works fine in stereo and everything.

I've tried and changed every setting I can think of and I'm tearing my hair out over this!

Thanks.