Broken lock button on iPhone 5

a few months ago my lock button on my phone stopped working. you can press down on it just fine, like it's not jammed or anything, it just doesn't do anything. i've had my phone for just over a year, a year and a week tomorrow actually. i've read different discussions about broken lock buttons and most of them have said to just take it into apple and they'll most likely replace it. but my problem is, i'm almost positive i don't have a warrenty on it anymore, and even if i did, would they still replacing seeing that they don't sell iPhone 5's anymore.