Unreal engine 4.14.3 crashing when starting up a project

Hi,

I have a problem with unreal engine when I start a project (witch i was working on for a while now) it just crashes
and I don’t know why. I have already tried migrating content to an other project but when i try to use any of that it crashes again. It’s exstremely anoying and i don’t want to lose all of that content i worked so hard on.
Sorry if my english isen’t correct it’s not my main language.
Anyhow i hope someone can help.
Thank you in andvance.