My level content disappeared for no reason that I can find

I have backed up my on a server - and 2 separate hard drives…decided to take a month long break from the project, came back to it a month later - During which I had recovered my boot drive and upgraded to windows 10…I install UE4…open up my project and all the content in my level is Black…I upgraded to the latest engine version…still black…all my blueprints are still in the content browser but everything in the level is just vanished…

I have no idea what happened here and a bunch of blueprints are erroring out with missed connections

Anyone have any ideas what might have caused this?