Items in Inventory and Chests Are Gone

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here
i thought i was able to update to the new Snapshot and all would be fine for my inventory

What actually happened was...:
but when i do i lose ALL my inventory and all my Chests Inventory

Steps to Reproduce:
1. i Updated my Snapshot and loaded the game like normal but then wheni get there i lost all of my items.
2. i then went back to 1.7.4 and i still had no items.
3. I had to delete my save game and replace it with a much older copy to regain all my Items