I was just playing games with my earphone on iPod touch, when suddenly the left side of the earphone stops working. At first the both was fine. The right side still in good condition. On the left side it stops working, when i twist and turn the earphone plug the left side hears little of the audio, when i stop the turning the audio stopped also. This is the 3rd time i am getting this. All of them are in the same case as this and i decided to change earphone. Now i'm getting sick of this. My theory is the wire on the inside of the plug is broken.
If they're at all like they used to be, those earphone wires will be super-fine. If you have the tools and the dexterity, you may be able to splice it. Otherwise, your best course of action is probably to get some replacement earphones.