My IPhone 4 lock button won't work....

For the past month, my iPhone 4 lock/sleep button has been really hard to push. I wasn't to worried until just an hour ago it stopped working all together. I try pushing it and it won't click, push down or anything. I've always taken good care of my phone by keeping it in an otter box, not dropping it, and it's never had water damage. I would take it to the apple store, but the nearest store is over 2 hours away... So is there anything I can do do rig it to work? Or even is there an app? Like how they made an app for people who's home buttons stopped working? Any help would be very much appreciated, thank you.