headphones not plugging in

a few weeks ago i plugged my headphones into my phone to listen to music and they didnt go in. i then tried another pair of headphones and they didnt fit again and another pair didnt fit. i really pushed them in and so many people have tried and its like they dont fit anymore. i also tried blowing into it to see if anything was stuck in it but nothing. I use to always listen to music on them and be on the phone with them and all of a sudden they dont work. any suggestions? and if its a problem with them actually phone and not my fault will i need to pay for it?