iPhone 5 sleep/wake button not working.

Take it to Apple, they'll replace it.

The same thing has happened to me. About two weeks ago, my sleep button started going out on the right side. You have to press the sleep button on the left side for it to respond. I have never dropped the phone and have it inside an Otterbox.

Make an appointment with a genius to replace it.

My phone has this issue as well but I will wait to replace it.

Mine still works, but I've noticed its becoming more flush with the rest of the case. Anyone else noticed something like this?

I'm on my 3rd iPhone 5 - first two had this problem

This is apparently a known iPhone 5 problem, though Apple doesn't discuss it much.

My first iPhone 5 sleep button was inoperable. They replaced it at the store. I had my 2nd iPhone 5 for the past 90 days. Sleep button worked great. All of a sudden, in the past 2 weeks, it started working only intermittently.

I had it replaced today at the store. There is a workaround they'll tell you about turning on accessibility features to be able to lock the phone.... no one wants to do this, of course.... have them replace the phone.

The rep I talked to says he sees a lot of these.

Hope this helps.