How to fix headphone jack problem?

This always fixed my headset problems for me http://howtofixstuff.blogspot.com/2012/01/how-to-fix-earphonesheadphones.html

Hi, you have a hardware problem in your computer. You can't really do anything to fix it yourself and even if you can you should not do it. Cause it comes under tampering the device and you will be hence voiding the warranty. I would recommend that you should visit any apple servicing center. Or at least give them a call on their live support number so that they can guide you more efficiently so that you know what you need to do to get it fixed. If the phone is in warranty then they would fix it for free but again they should not know about you messing with the phone by tapping with the wire as you mentioned. If they found they can void the warranty and you will be then charged for the same. So try to hide it if you can. If the phone is not in warranty then you should tell them straight away what really happened. It should not cost much since its just a jack