Headphones don't go into iPhone 5c So I had these headphones and they worked for about a week and then suddenly they just don't fit into my phone. I have to press them really hard and hold it there. Other headphones fit just these don't. They're Apple headphones btw.
I recommend you don't try push them in to hard just to insure no unwanted damage, best bet is to go to apple. With these types of faults there the best to fix it.