Chest data deleted, player fell through the ground, all mobs killed and fell through the ground

When I logged onto my main survival world, I had fallen through about 20 blocks into a water filled cave. When I went to go back up. I lot of raw beef and leather were on the ground, but no exp. When I went back up, my cows were gone. When I went to put away the raw beef and leather, I noticed that my double chest was separated and all items in it were deleted. Last thing i did before I logged off was check my map room to see if was still there. It was not. I can recover from this but still it's very annoying.