ADOBE DELETES ANNOTATIONS HELP

[Alexa5E9E]

I'll make this short. I'm a college student. I have a macbook pro. I was using Preview to view and annotate my textbooks but Preview was deleting my annotations so I switched to the free, downloadable adobe reader version from the app store. I do not have anything special, it is just regualar adobe. There is nothing special about my mac either, I use it for regular purposes. For the most part everything was saving fine except for a few issues here and there (one of the files was corrupted so it wouldnt save, but I did research and was eventually able to get it working again). My mac was prompting me to do an update last night and I believe it did it. I ususally ignore the updates for this very reason which is why I think it was the update that prompted this change. This morning I woke up and 90% of the annotations I had in each textbook were completely erased. All my highlights, notes, arrows -- gone. I have no idea why this would happen when I had been saving both files consistently during every use. Everything was there just last night. Even when I would save, close, and reopen it would be there. Now all the annotations are gone. I tried to find a revert option but it is blanked out. Please help 😕

Also, it is liked it picked and chose which ones to delete. In one textbook, only chapter 4, 5, and part of 6 were deleted. In the other, only the very last chapter I had been reading was saved. 

[Alexa5E9E]

I right clicked on both of the textbooks and clicked "get info" and this is what came up. For the biochem textbook (on the right) it says the file was created on feb 23.....I've had this textbook and have been annotating since the beginning of january