"Unexpected end of ZLIB input stream." Unable to open world.

Hello friends!

Yesterday I started a Minecraft 1.2.5 world for funsies and after I was done playing on it, I saved and quit as usual. However when I went to go play again this morning, it suddenly disappeared from the worlds folder and when I opened it up in the latest version it returned to the attached error.

Here are some things I have already tried:

• Copying and pasting the files into a new folder.
• Copying and pasting just the region and data files into a new folder.
• Attempting to restore previous versions of the file.

 

I have also attached the files for the world below. (I can't attach it as a .zip file sadly since the file size is too big, however all files are in the correct spots.)