Plex will not play a particular movie

Did you re-run the ‘Scan Library Files’ command after replacing the file?

If that doesn’t resolve it, there’s no need to edit the database directly. Simply remove the file, then run “Scan Library Files” (this will remove the db record). Then put the file back in its original location and run “Scan Library Files” again.

If that still doesn’t resolve it, do the “Plex Dance” for a more thorough cleanup.