Rebuild/Repair Music Library file?

Hello. I house my music files (over 400GB) on an external hard drive without a problem--until today.

When I opened the Music app today the only files are showing are those that I purchased from the Apple Music Store. In addition to the missing music files my carefully-curated playlists are missing. I tried to re-direct Apple Music to the files on my external drive (no dice). I tried removing the current Music Library file to see if Music would rebuild the file after I re-established the path to my files, and still no dice.

Is there a way to rebuild/recover the path to my files on the external drive, or resurrect my playlists?

Running OS Catalina (10.15.7) on an older 27" iMac, but again, the files are housed on an external drive.

Thank you!