Acrobat reader has deleted half of my assignment1!

Help PLEASE!!!! 

Using a MAC 

I have been working on an assignment with acrobat reader and iv gone to save it. It has come up saying it cant be saved and when i clicked out of it all my questions were gone, but my answeres still remained. i closed it and opened it and it had totally removed all my progress. Like half my assignment was gone. 

Before i realised this i had added my name to the assingment as i was about to submit it and saved the document. 

I scrolled down and realised that over half my answers were missing and i had just saved it as that!!! 

Is there and way to retrive previously saved versions?? 

I tried in my recent files and clicked on the one most likley to be the full version but it comes up saying the file is no longer avaliable!!!

P.S I absolutely HATE using this. Totally not user friendly and iv had nothing but issues for over a year from the beginning of my course.. If anyone can suggest how i can save it from my collage portal to something different if thats even possible. That would be greatly appreciated.

Thank you!!!!

Totally computer illiteriate here so please use jaron explinations.