Adobe lost my files

I had stored some pdf files with annotations. I replaced them as I added new annotations. Adobe lost my current files dated yesterday and went back to the older copies dated July 28th. Thus all my most recent annotations were lost. How do I recover my most recent copies?

e.g. I stored filename.pdf on July 20th. I then read several pages, making annotations, and re-saved the annotated filename.pdf on July 28th. I then made some more annotations and re-saved filename.pdf again yesterday. Today, Adobe lost yesterday's copy and replaced it with the July 28th copy, thus losing all my annotations since the 28th.