- Go to Settings and then swipe left to applications > photos+camera (pictures+camera).
- Scroll down to the bottom and reset camera which is to return a default camera settings.
- If it does not help, switch to the front camera (optional) to see does it make a difference.
- Reset your phone. Press and hold the Power and Volume down keys simultaneously until you feel the phone vibrate. After this operation, you may need to set the date and time on the phone. Note that this does not remove any settings or your personal content.
The previous actions usually solve your problem. Make sure that your phone is running the latest software. Check also that your phone apps are up-to-date to the latest versions.