Whenever I entered a certain area in my world there was considerable lag. I entered it and logged out because the lag was so bad (the block reappearing glitch was happening repeatedly) and when I logged back in only the chuck I was standing on appeared and the rest of the world is just a void. I have not found a way to fix this problem anywhere.
Once you're in there, find the folder that corresponds to your world and make a backup copy.
Next, download NBTExplorer and unzip it. Launch the program, then expand the "saves" folder and look for the folder your world is stored in.
Open the "region" folder inside that one. Expand "level.dat" and then "Player".
Take note of "SpawnX", "SpawnY", and "SpawnZ" (the ones inside the Player subfolder).These are the coordinates you'll appear at if you die.
Expand the "Pos" group, then change X, Y, and Z to your SpawnX, SpawnY, and SpawnZ. Hit save and then quit.
Start up Minecraft and open the world. You should appear at your bed. If the game is still lagging out massively, you may have an excess of mobs (a rare glitch that fills the world with sheep, pigs, etc.) If that's so, you'll have to nuke them with MCEdit.
If the lag is gone, though, see what happens if you return to the glitched spot. If it causes you to lag out once more, you can probably delete the defective chunk with MCEdit and then let it regenerate.
Either way, try this fix to see if you can even get back into the world.
Didn't work, even though I changed my character position it still spawned me in the middle of the only loaded chunk. I guess I'll try the MCedit thing again but it did not work before.
%appdata%\.minecraft\saves
Once you're in there, find the folder that corresponds to your world and make a backup copy.
Next, download NBTExplorer and unzip it. Launch the program, then expand the "saves" folder and look for the folder your world is stored in.
Open the "region" folder inside that one. Expand "level.dat" and then "Player".
Take note of "SpawnX", "SpawnY", and "SpawnZ" (the ones inside the Player subfolder).These are the coordinates you'll appear at if you die.
Expand the "Pos" group, then change X, Y, and Z to your SpawnX, SpawnY, and SpawnZ. Hit save and then quit.
Start up Minecraft and open the world. You should appear at your bed. If the game is still lagging out massively, you may have an excess of mobs (a rare glitch that fills the world with sheep, pigs, etc.) If that's so, you'll have to nuke them with MCEdit.
If the lag is gone, though, see what happens if you return to the glitched spot. If it causes you to lag out once more, you can probably delete the defective chunk with MCEdit and then let it regenerate.
Either way, try this fix to see if you can even get back into the world.