Time reversing my inventory or structures

I'm playing on an old survival no cheats world. The first time it happened was when I first logged on, I found out that my iron was gone, and some sugar cane too. Then, later on after I'd harvested the sugar cane and built an animal pen, my game crashed. When I got back onto the world, The sticks I had left over were still there, but the pen was gone. The sugar cane I'd harvested was also gone.