Level Disappearing when starting game

I am making a very basic maze game. I just finished level 5 i hit p and my level goes away. I don’t know what the problem is. I don’t know what i did wrong. i attached my .blend file. It someone can help me with this i would appreciate it. thank you.

Attachments

Maze Game.blend (1.41 MB)

Your level is set to invisible in the physics panel, un-click that and it will all show up fine!