My headphone jack has problems too as I'm on my third tour but too lazy to go for my fourth. Basically some headphones would work when playing music but others would stop playing immediately after I even move the cord a little bit as it senses a disconnection. Oddly enough, this is a known issue and you can tell if you have a good audio connection or not by looking at the speaker/headphone strength indicator in the bottom right corner of the music player. If the headphones looks cracked, then the connection is weak.
Only used mine once just after I bought it just to make sure it worked.... not sure if it still works or not..don't really care as long as the rest of the phone is working.
