It sounds like you renamed the files themselves outside of MediaMonkey (this should be avoided). After that it's unclear what you did, which means it isn't clear what's the best solution at this point.

You could start by checking Dead Links. Do you have lots of files there? If so, do they still show Rating. If the case you could use Locate Moved/Missing Files on these. It may solve part of the problem.

Hi, I've spend a long time to rate the songs in MMW5. I use it so select and organize the 10.000 songs I have.
After doing that, a couple of weeks work listing to all songs and where needed using auto-tag to correct the name, artist and year, I used mp3tag to rename the files based on the adjusted tag values.
When opening the folder in MM5 again, after resync, it turned out that a lot of the ratings are missing. In MM5 that is. When I open the folder in Windows Explorer or MusicBee, I still see the ratings I've entered in MM5, however, lots of them are missing when I use MM5 to scroll through the database.
Rebuilding the database didn't work. So how do I get the ratings back in MM5?

T.i.a