Can't break blocks in minecraft?

So every day I babysit this kid, and we usually play Minecraft together, but today when I got here he was fooling with the "Super Secret Settings". I got them back to normal, and now he can't break blocks. HE IS NOT IN ADVENTURE MODE <- I made sure to switch him to GAMEMODE 0, not 2. Just to make that clear since every answer has that there. He is in creative, and survival normally.

He is in a single player world, but even if I open LAN on my laptop he can't break blocks. Can anyone help?

Added (1). Also, all of the controls are correct as well. The option is on the left mouse button.

Guest

Super secret settings merely changes the screen effect, like making it look pixelated or black and white. It's purely visual and should have no effect on gameplay.

I would try Rebooting minecraft (the launcher too) or trying it on a different world. Also, make sure you do not have a sword equipped. If you have a sword out in creative, you can't break blocks.

SPECTRAL