I set my external hard drive as the location for Music. It was there, but upon restart, it is no longer listed in Music

All my files 110gig transferred and were visible and accessible in Music. When I restarted the computer, with the hard drive connected, the files are still on hard drive but are no longer listed in Music?

I have tried changing then Music Media file location and then changing ti back to the hard drive - but no luck.

I CAN select a song from the files on the hard drive and it plays and adds that one song back.

But the "songs" only shows 360 files!