My house and everything I've ever placed or created, are completely gone

I just logged onto a survival world of mine on 1.14.4 after taking a break for a bit, and I found everything, including my crops, my animals, my house, my builds, etc. completely gone. Blocks that I had broken reappeared. However, I still had everything in my inventory that I had previously. It seems as if everything in the world was reset, excluding my inventory.

I do not believe this is a backing up issue as I have backed the world up when I've logged into the world in 1.15.2 and also 1.14.4 (which is the version which I predominantly play on). I believe that I left the world while I was in 14.4.4 the last time I played in it when everything was fine. 

I apologise if I haven't set this out correctly or have put my issue in the right place, as this is the first time for me on this site. Hopefully someone can help me with this.

Thanks.