Go to the Camera App. Touch it to put phone in camera mode. Now touch the icon in upper left corner that looks like a flat toothed gear. Now scroll to the bottom where in reads "Restore defaults" click on that. Now your camera flash should work. I had the same problem. The flash symbol was viewable, when in camera mode, but not activated. Some how I deactivated the flash. Clicking on restore defaults reactivated the flash. Thank you Lord! Hope this helps!
While in camera mode, look for an icon that looks like a lightning, that's the flash for camera. Hope that helps! :)