My headphone

What headphones do you have and what is not working on them? If they are the Apple Earbuds supplied with your phone, they came with the same one year warranty your phone had. So if you have owned them longer than 1 year, they are no longer covered by warranty.

And when did you purchase the phone? As I said above, if you are past the one year warranty, the headphones are no longer covered.

Take your original purchase receipt, your phone and the headphones to the Apple Store and they'll replace them.