Headphone Jacks and Audio Problem

Hello,

I'm using a Dell XPS M1330 laptop with SigmaTel High Definition Audio. On the front side of the laptop, there are three jacks: two headphone jacks (the left and middle ones) and a microphone jack (the right one). Up until last night both headphone jacks worked fine, but this morning I tried watching a video and I got no audio from the left headphone jack. The middle one still works though. The audio plays fine without headphones as well.

Thanks for any help!