Hello there,
I am working on building y school in UE4. I learned it through experience, and I have 80% of the school done. The trouble remains, I tried rebuilding Lighting, and all it did was make most of the thing go black. When I used to hit Play before, it kinda looked fine, but now, its hopeless…Is my project ruined?
Obviously I am doing something wrong… I read something about 2nd UVmap in this case, but I have no Idea what it is, and other guides have not been helpful yet, as they are out of my understanding.
I need to Know how to fix this, all Step by Step, and in simple words, also explaining what it does…
I created my 2000+ models in Blender.
Please respond ASAP, and keep in mind, I am just a NOOB… 
Hi Ziad,
Your project is not ruined, but there may need to be some things setup before you can properly build lighting, like a lightmap UV. This is required to get good baked lighting for your meshes and it requires that you have no overlapping UVs in order to do so.
You can read about lightmapping here in the documentation: Understanding Lightmapping in Unreal Engine | Unreal Engine 5.1 Documentation
You may also find it helpful to read through this Wiki Guide for Lighting Troubleshooting and Tips that I wrote a while back : A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
It can walk you through some setup for your Lightmap UVs and other common questions asked about lighting in Unreal Engine 4.
Thank you!
Tim