1. Try a Restart by pressing the sleep/lock button until you see the slider. Slide to power off. Restart by pressing the sleep/lock button until you see the Apple logo.
2. Try a Reset by pressing the home and sleep buttons until you see the Apple logo, ignoring the slider if it comes up. Takes about 5-15 secs of button holding and you won't lose any data or settings.
3. Remove apps from Recently Used list...
- From any Home Screen, double tap the home button to bring up the Recents List
- Swipe up on the app preview card
- Press the home button when done.
4. If still a problem restore with your backup.
5. If still a problem restore as new, i.e. without your backup. See how it runs with nothing synced to it.
6. If still a problem, it's likely a hardware issue.
I have the same problem with ma iphone 5. When i upate to ios8.1.2 from 8.1.1 then camera flash and flash light was working for the first snapshot and first time tap on flash light..then i did not work for next use..after some time, it again start working for first time and then again not working..and so on..when i updated it to 8.1.3..then the camera flash and flash light is completely out of order..i do hard resetting but the problem is not solved yet..pl tell me what to do?