All my imported meshes are all black after building and I don't know what to do

Hi, I really need help ASAP as my project is due in 2 days… I’m having trouble building my game level as after building, all my imported static meshes goes dark and i dont know what to do. I’ve looked at other answers and they mentioned the rebuilding of the 2nd UV channel. I dont have any clue what this is and if somebody can help me I would be really grateful. Below is the picture of the problem with the right being the static mesh before building and the left being the mesh after building. If anyone needs the static meshes. Please comment and I would gladly send them as I cant upload them here as the file type is apparently invalid. I dont know what im doing nor do I know much about Unreal Engine. But If anyone is willing to help, I would be grateful. Thank you

The 2uv channel is used for lightmaps. You can tell unreal in the mesh editor to make one based off of the uvs you already have or in a 3d program like Maya you can unwrap the model with a 2nd set of uvs and tell unreal to use that as lightmap.
Also, are your lights static or dynamic. That will also deteine what you need to do. Because dynamic lights don’t get baked into a lightmap.

I know its a bit lazy, but since I need to go in less than a few minutes, my suggestion is to google “ue4 lightmap tutorial” which would give you quite a few videos and other resources to get it going.