That problem has got me stumped
I have loads of .txt files on my desktop full of snippets of information (like ToDo.txt, Ideas.txt, etc...) but I've not had this problem yet.
Unfortunately I don't think your information is still there, as the "size on disk" is always bigger than the actual file size due to the way the file system works. The smallest cluster size your drive can store is 4k, so a file with an actual byte count less than this still takes up 4k of space on the disk.
Here's an example of my ToDo.txt file: