I completed building several houses in my world last night. I know it saved because the last house I was working on is still there but the progress in my other houses aren't there.

I discovered this when I tried to log into my world using another xbox we had in the house.  When I loaded the game,  it said it needed to activate the resource pack and download it. It instantly was messed up once I loaded it and has yet to fixed itself since then. I tried loading another one to see if it was ok but was unable to use that one as well.

One house is completely gone, another is missing 2/3 of it, another has a couple things left inside but most of the progress is gone.