How can I recover the my unsaved/corrupted file? i

I write notes on adobe acrobat and i saved the file but when i opened it an hour later, there was another conflict file and all the notes i had made between 7pm and 9pm had vanished. 

I went to my files adobe.acrobatreaderdc.protectedmode then AC and have found the files there but everytime i tried to open them they say "Adobe Acrobat could not open file because it is either not a supported file type or because the file has been damaged (for example, it was sent as an email attachment and wasn't correctly decoded). To create an Adobe PDF document, go to the source application. Then print the document to Adobe PDF."

I spent two hours annotating that document and need it for my exams next week. Please help me recover my notes.