My brother and I were working on this world for almost a year now. We've been using the Coastal Village seed because it had everything we needed for this project. We've built so many things in this world and spent a lot of time adding little details as well. I've been working on it for hours every day to make this quarantine better, and it really did. 
Now today, I tried to join the world but I was in survival mode. I thought I accidentally picked another world, so I saved and quit, and tried to join the skyscraper project world. 
Turns out, it's the same exact world as that survival world. I switched to creative, only to see that all of our progress wasn't there. It loaded up the same world, without our structures. I did found multiple ruined portals though. It seems as if the seed updated, and deleted all our progress. 
We terraformed a whole entire desert next to the coastal village and turned it into a coral reef ocean. it took so long, and it really sucks to see it all go to waste. 
I made multiple copies of the world, but those were much older versions, like 5 months old, and rebuilding all of the things we built would take too long, and I honestly feel demotivated to do so.
Is there a way to mess with the game's files to find my old world that's missing?

The pic below shows 4 pics of how the world used to look like, and how it looks like right now. It's the exact same file. Same world.