- Go to the settings menu, and scroll down to "About phone." Tap it.
- Scroll down to the bottom again, where you see "Build number."
- Tap it seven (7) times. After the third tap, you'll see a playful dialog that says you're four taps away from being a developer. (If only it were that simple, eh?) Keep on tapping, and *poof*, you've got the developer settings back.
mtp: Nexux 4
So YMMV, you may have to farkle with this.