1. Go to the Settings menu and scroll down to 'About Phone.' Tap it.
2. Scroll down to the bottom again, and you'll see your phone's 'Build number.'
3.Tap it seven 7 times. You'll see a pop-up showing how far you are from enabling the Developer settings. Keep tapping, and you'll magically get your 'Developer Settings' back. Neat, isn't it?
If you don't know what it's used for, it would be best if you do not enable them.
Hope this helps!