So me and my friend have been working on a world for at least 6 hours. We built our houses, got a lot of loot, found a village, made a farm etc. I saved at loaded the world the next day and it worked fine (for 3 days). Last night, I did the same thing, saved my world and closed the game. But when I opened Minecraft (Bedrock) today and tried to load my world, EVERYTHING WAS BACK TO WHEN I SPAWNED FOR THE FIRST TIME! I had no items, there were no buildings, my house, farm, everything was gone! It was just like the world had literally reset itself and I was back to spawn where I started - back to 0! This happened in the past on other worlds and I couldn't find a fix so I decided to play on my friend's world instead. This had never happened to him, and he was playing on MC Win10 Bedrock as well. I've looked this up on the internet for 2 days now and can't find a fix! Please help me to find a way to get my world back!

The pic below has 2 of the same world. They both have the thumbnails of the world when I saved but they load as pic 2, which is spawn. Since the thumbnail is still there, that lead me to believe that my world might still be recoverable somehow? 

P.S: I may have found the old MANIFEST file that my world could be in but I can't seem to open it (its in the lost file). If someone knows how to open MANIFEST files from the lost folder, please help!