My worlds chunks just went crazy, so i changed the chunks (via a back-up i made on my pc through iexplorer) file. That didn't help so i used my back-up to replace the level.dat file, and now my chunks are normal. Everything is normal for me but multiplayers get the messed up chunks when they visit my world, the chunks are shown incorrectly.

Sorry the "affects version" box is informed wrong, the pocket edition isn't listed there