Generally, once a file is corrupt, it's gone. So what I'd do, is just recreate the changes using one of your slightly older versions of the file. This time taking care to make sure you know exactly which one you're editing. Maybe saving a copy to a USB flash drive in addition to uploading a copy somewhere.

In the amount of time you've spent looking for ways to recover the file, you probably could have recreated the changes and been done already. Always be sure to consider how much time and effort each option takes. Obviously if you could have quickly found some program to recover the file, that would have been best, but when that search came up empty, you should have switched right over to just recreating the changes. Effective time management skills are something you need to succeed in school.