Lock button not working?

So I went to get my phone this morning and it turns out the screen had been on all night (charging). I tried locking it and ir wouldn't. The other features of the power button work (screenshotting, etc) but my phone won't lock or shut down. I saw on another thread to try force shutting down and I tried it, with no luck.

So now the only way I can wake up/lock my phone is through double tapping the screen, which isn't a big deal, but I still want my power button back. Help?