Module.dll error.

I am working on a project and I am having issues with making something work how I want it to. So I decided to make a c++ class thingy and see if I can find a way to import the blueprints I made into it. When I made it. It was obviously not what I wanted so I just exited it without editing anything. Now when I open the project I get modules missing or built with a different engine. I say go ahead and rebuild, and it fails. Any help would be nice.