I am  building in "Creative" mode and in "Peaceful" Level. My World is all broken up when I logged in this morning 4/11/20 about 8am. I read I might have a backup, but my System's Library/Aplication Support doesn't not have a Minecraft Saves Folder. Before, I had dug out many rooms in a hill, with entrances all around. I had a floating house made on a pillar, then removing it. Today, half the floating house is gone. I started underwater where before was an underground room. I found partial stairs to the outside on the wall of this open cube space.  Everything is gone. Huge hillsides are now straight vertical crevices. There are floating chunks of hills everywhere. I can move around without a problem.