Hey, you likely twisted or pinched the wire going to one side of the headphones causing it to finally break. It's so common and not much you can do about it. If they're iPod headphones, and you're still under 1 year warranty or Apple Care, Apple will send you a new pair for free as long as you send the old ones back in a box they send you.
I just decided to get the dock AV out thing. Although for a little while after I tried the alco trick it worked for like 5 minutes
