The left headphone wont work

I bought my Iphone 5c in late October and the sound worked perfectly for 3 days or so. However ever since then the left headphone wont work, it also gives of a really strange sound from my speaker when i use my iPhone for it. The headphones never work on phone calls because the calls sounds so static you cant work out what the other person is saying. I have look up this question plenty of times and they all have the same answers which never seem to work, I have turned mono tone on and my left and right slide bar is perfectly in the middle. Will I have to replace/fix my headphone jack or what?