I know this isn't really a bug, but I would like advice on how to fix it nonetheless.

So I've spent the last week working on my world, and I was using command blocks to add some particle effects. I accidentally added an extra 0 to one of the blocks, and now the world is utterly frozen. This issue has come up before, and I usually resolve it with /fill, but the game is completely unresponsive. I waited five minutes for my command to load, and eventually the game crashed. I really don't want to delete the world, and I'm afraid reverting to a version before 1.8 will cause corruption. If there is any way to fix this (ie, reverting to a previous save,) please let me know. I worked really hard on this world and I don't want to lose it.