All of my chests are empty

I turned on Minecraft and expected everything to be where it was last time I played it.

When I got on my world, my inventory was empty, as were all of my chests. All of the item frames that were on the wall were just items on the ground, and some of my doors were just missing.

Steps to Reproduce:
I don't know how to trigger the bug. When I tried to log on a few days ago, the servers were down. When I logged on today, everything was gone. I just want to get my stuff back.