Did... Did that REALLY just happen?

Well, about 5 minutes ago I tried to play minecraft after really not having much trouble with the program at all.... and when the game loaded I spawned in complete darkness unable to move getting killed by an invisible force. I re-spawned close to my base only to be confused when a lot of what i built had been rearranged. I entered my door and found that a massive chunk of my base was gone (conveniently it erased my crafting room filled with my diamonds, obsidian, gold, iron, and redstone) My gate to the nether along with my lavafalls and waterfalls were all intact. It seems most of my world has been reset into a new world with select areas that have remained the same. Unfortunately what remains is mostly useless projects i was doing. I May just start an entirely new world because Its pretty frustrating to see some of what I had and not have the rest.... Any ways to fix this problem or anyone else had the same experience?

well as for the resorces use invedit to get them back.

Jolt had the exact same problem he lost his entire inventory but not his base.

THAT NEVER HAPPENED TO ME