Best answer as chosen by user cag8f: Posted in the Apple forum too.

by R. Proffitt Moderator - 1/8/13 11:12 AM

In Reply to: podcast ratings lost in itunes upgrade by cag8f

-> https://discussions.apple.com/thread/4669180?start=0&tstart=0

I see folk have reported such in the past and such ratings are in your library so try installing the last backup and see if it comes back. Again, many folk don't backup so they can't try it.
Bob