I was in the process of digging a massive quarry (about 35x35 blocks). I had a jukebox in the centre of the quarry and until now was able to remove it easily, but shortly after I removed it today the game froze and then crashed (all the times I've removed it before I've been using this Version; 1.4.7). Upon reloading my world everything was black, then I started to suffocate (I realised that I was buried... initially just thinking I'd been buried just below the ground I was standing). I started to dig up and eventually got to the floor of my quarry, but it turned out I wasn't buried under the floor, the whole chunk I was standing in had been restored (just that chunk, as the rest of my quarry was fine). It initially took a long time to clear that land and I don't want to waste diamond pick axes re-clearing it (plus some water and lava has spawned there). How can I restore my world to before the crash? What caused this to happen? I'm fortunate that this all happened inside the quarry as the outer walls of the quarry are a tall tower I'm in the process of building (lot's of time has gone into this). I've Attached a screenshot of the quarry after the error along with the error report.