ITUNES On External drive

For the past three or for years I have been keeping iTunes on and external drive and never had any issues. Today however I clicked on iTunes and it said it could not find the file so I clicked on the drive and opened the file. The problem being when iTunes opened the only music that was there was the music I have downloaded over the years from iTunes. None of the CD's or vinyl albums I put in iTunes we're there. Not to mention the fact that my playlists were gone. Anyway I went to iTunes preferences advances setting and changes it from iTunes media to my iTunes file on the external drive and that did not fix it. Spoke to Apple support and they had no idea how to fix the issue. If I play music from that folder then the songs will show up in iTunes. Not sure why iTunes will no longer access that folder. Wish I could find the post. When I first started doing it this way the first few times you had to do something like hit control alt delete to be able to select that folder in iTunes. Would greatly appreciate any help I can get on this issue. Thanks Dave