Random glitch with viewport?

I was building an extremely simple level and this happened to the project as a whole. I’m not sure If I pressed something by mistake or what. I can open another project just fine, but my 3-day one here is no longer visible. Shadows look slightly messed up when I play.

Update: I am not able to move anything around at all in the viewport.

What is “this” exactly?

Opaque meshes are transparent, and glitching. I also cannot move anything without holding the shift key. It also sometimes goes completely white if I move my camera around.