Can't spawn in prefab from editor

hello i’m trying to spawn in prefab from the editor but it won’t let me. I try clicking and dragging it to the scene screen but nothing happens and theirs a cross symbol their. and when i click on the prefab it dose not let me inspect it. probably something simple but its gone over my head can someone help me out here?

EDIT:

i tried re-importing everything and now it gives me the add icon when i drag to the scene but nothing happens.

hope this helps

maybe something that make help is i had a windows update then this started to happen idk how those are connected if they are.

An image would be helpful.