Random black rectangle

Hello!
I was working on a Photoshop project, but after I opened the file and made a couple modifications, a black rectangle strangely appeared on my screen. I can't switch to any tools, can't save, can't close windows, can't select layers, the only thing I could do is scroll through my layer. So techincally my screen is frozen.

This is really frustrating for me since I don't want to rework my entire project, so if somebody could offer a solution, I would gladly appreciate it!

Sincerely, Zinger.