I had a similar problem with my Toshiba Satellite M100. I could only get mono, but I had to do some strange stuff to get that to work (it could only be plugged in half way and held at a certain angle). As it turns out, it wasn't a hardware thing at all, but a software thing. I reinstalled the audio drivers and I got my headphone sound back. You might be able to do something similar. Goodluck!