[MC-59294] 14w26a / 14w26b saved corrupted blocks / Blocks have dissappeared in14w26c

all wooden logs, wooden fences, chests, enchantment tables, red stone, pistons, sticky pistons, crops, doors, bookcases, stone blocks, stone half slabs have disappeared..... in fact all that is left is cobblestone and wooden planks. the environment seems to be fine with all mobs present and correct. worst thing is i have no back up......
annoyed.

what has happened?

Mod note

https://mojang.com/2014/06/minecraft-snapshot-14w26a/

If you are updating from 14w26a or 14w26b, your saved world has corrupted blocks and it will be heavily damaged once you open it in 14w26c. Please use a world backup that was saved with a pre-14w26 version.
Never use snapshots without first making backups of your saved worlds.

https://twitter.com/SeargeDP/status/491305003278401536

Fix by MCEdit

WolfieMario managed to make an MCEdit filter called "Uncorrupt14w26a+b" which fixes the corrupted data from the worlds corrupted in 14w26a/b: http://np.reddit.com/r/Minecraft/comments/29551r/if_you_corrupted_a_large_project_or_lost_a_large/cihnyjq
_{Thanks to Dlawso the Really Lucky Rabbit for digging this out}