I've probably just done something quite stupid, and renamed / changed the order of the packages in my project manually via the src folder at eclipse workspace.
After doing that I had to fix every class seperately and rewrite the package it belongs to, on its top line.
The problem is that now, it seems like my project doesn't even recognize its classes. they don't show an error if they have one, while the project itself always shows a red error. When I run the project I get
Error: Could not find or load main class".
I tried Project -> Clean or manually choosing the main class, but it didn't work.