Once again, my tools don't work on the world.

Just like the other day, my tools will only work on props, not on the world. I don’t know what caused it, but can I please get some help? I don’t know what changed. If you need to know something, I can probably tell you.

is this on single player or what?

Also have you got prop protection?

Have you downloaded This addon?
It stops you from using the toolgun on the world.