Well, there are a few ways to solve this. The easy way would be either to call the manufacturer (At
(860) 434-9190, more info here) and see if there is a warranty on the item. Second, you could just buy a new pair, which is probably not the best way. Third, you could actually splice a new jack onto the headphones with a little soldering skill. You'll need to:
1)Cut the ******** the end
2)Strip the wires off the jack (and the replacement jack)
3)Solder the wires together (Matching black to black, red to red, ground to ground, etc)
If you've never soldered before, see if you could get a friend to help.
Here is a video tutorial of how to solder, if you wish to attempt this yourself.