I just figured it out. This has worked for years up to about a month ago. I was trying to figure out what has changed and the software for the external drives was updated about a month ago so I put all the music on the hard drive, updated the location, re-scanned and am back in business. Thank you for the suggestions. Have a great day!!

Then check the full Path in MediaMonkey with the full Path of the file in File Explorer. They should match and probably don't. Is that the case?

They do not play when selecting in MM. I get an error stating that the file is inaccessible

Do they play in MediaMonkey (selecting from MediaMonkey)?

How do the files present missing?

Yes. The drive letter is visible for the missing files when shown in the library and also when i go to locate the files. Very strange

Do the files show a drive letter in MediaMonkey (in their Paths)?

All of a sudden 80% of my library is missing. Not sure what happened but I need help. I have a lifetime license. Have been using MM for years but all of a sudden the software can't seem to find most of the library. Library settings are accurate. The songs are in the locations (external drive) specified in manage database. What am I doing wrong??