Empty chests and inventories

I loaded and played a world in survival (MC 1.7.2/4) and accumulated a lot of valuable resources. Later I experimented with snapshot 14w05b in a seperate world. I accidentally entered my survival world, thinking it would be fine, but my inventory, chests and everything that can basically hold items is emptied. I do not know how to fix it exept to /gamemode 1 and retrieve my items from the creative inventory.