Screen won't go off!

I managed to fix a problem that I have been having recently where the screen would not dim. I looked for rogue apps that may be keeping the screen on but that did not amount to much. It was a relatively simple fix. I looked in Settings -> Display and noticed that under SLEEP there was no time selected which is strange because I definitely had it on 1 minute a while ago. The option to not select any sleep delay wasn't even available and yet there seemed to be no delay selected. Check out your settings and you may be able to fix this problem as well. However I am at a loss as to how the phone managed to unselect ALL the options.