All four screens are black

New to Rhino, just trying to make a simple model for a set I’m building. I have imported some rhino files for the chairs so that I didn’t have to build them all myself so I feel like the size could be the issue - BUT when I started adding emission to the walls so that they were lit up, I went to do the last wall and now all the perspectives are all black.

Pls can you help me fix this I need to give in my model asap

Hi Leah -
Please run the Rhino SystemInfo command and copy-paste the result here.
Also, please post or upload the 3dm file that is misbehaving on your system.
-wim