Unreal Engine has stopped working

Hey guys,
I’m experiencing a really annoying problem right now and probably my project is totally fu**ed up :frowning:
I worked hard on a project since yesterday and everything worked fine. But now the project has crashed and I couldnt open it again because there’s the error: “UNREAL ENGINE HAS STOPPED WORKING” after initializing(70%).
It was a quite hard exercise for my PC before it crashed. I was copying a lot of actors at once, but normally my PC can do this.
Specs:
8GB RAM
i5 4460
R9 380 4GB

I already updated all the drivers and got some space on my nearly full SSD.

I hope you can help me!
Thank You