so i went into my singleplayer minecraft world (duh) and i left the nether to get some cobblestone for a nether highway (which is the one thing that is still intact, i only have 2 but still im mad) either way, when i went back, my nether portal was different. it was surrounded by nether bricks and had no corners. it should be pretty obvious that now it did have corners and had no nether bricks anymore. i thought that maybe it was a different location at first, and realized that it was the right location. i had noticed major chunk errors in my ravine, which was covered in magma blocks and cobblestone and had iron golems and villagers in it before. this was my house btw, so i was really dissapointedwhen i saw that it was covered in more stone, my villagers and golems probaly suffocated and all died, and my storage down there was gone due to chunk errors.there was also a few randomly generated chunks that were higher then the others and my trader llamas died for some reason. there werent any chunk errors where they were. also i havent upgraded my world in a while and yestorday it was fine.

also, i went back into my ravine... and most of it was fixed! most of the villagers survived with 2 exceptions along with the place they live. my llamas also didnt make it still. also a chunk duplicated.

nevermind. it was just 2 ravine parts split, but either way, the world corrupted from trying to put it on an earlier version to remove the chunk errors, which  it did, but i lost everything that wasnt in my inventory. and yes its backed up.