So my friend's minecraft world got updated yesterday, and I apparantly have lost all my inventory items. I still have my armor and elytra as well as the map I had in my off hand, but the rest of my inventory is completely gone. I appear to be the only member of the group affected by this and I know I had a full inventory (with shulker boxes and such) in my possession just a few hours before the update. 

My freind even tried to update the world to an older version to restore it, but that didn't work either. Somehow updating the game has affected my playerdata.