Lost all Levels, Inventory & Armor

I logged in as usual today but my Inventory, Levels & Amor are missing. As if I died but I saved/exit my game at level 37 with everything in my In inventory, and I was wearing my enchanted diamond armor (not easy to get!). 

I play survival on hard with no cheats so loosing my Inventory is like starting over.

I don't know what to do so I am just going to leave beta and start a new world on original version....... thanks anyways