GORDON80  It run for 6 hours and found 1 missing song...

I came across this one, which seems to work fine:

Music Folder Files Not Added v1.1

It found hundreds of lost files within minutes, which I could add to my library or delete. Nice!

You find it here:

http://dougscripts.com/itunes/scripts/ss.php?sp=musicfolderfilesnotadded  
(Version 1.7b2)

GORDON80  Any news about this desired program?

I just tried it for the first time - version 1.7.

It was described as easy to use... but I cannot get it going. In the "main" tap there are the compare options - great. :-)

However it doesn't find any duplicates here... :-(

In the "search" tap I can chose the directory to search - great. :-)

Well, within a second it lists thousands of files... but none of them are really duplicates... :-(

Very confusing. Why doesn't it work? Please make it work - I would buy it right away. Is there anything else out there that does the job?  
(Version 1.7.3)

GORDON80  I tried out this secure looking program during the trial period using it internal and on an external disk. On the external disk I encrypted a folder with iTunes and Papers. The Papers folder one day had just disappeared just before the trial period exceeded and I created a sparse-bundle image for the new file I got from a back-up disk. The library in the iTunes folder crashed and I took an older one from the last back-up as well. I think the files will be damaged always when you turn of the computer while safe is open.

Now that the trial is over I cannot build new saves, as to be expected. What is annoying - I cannot change any file within those "saves". It means that I cannot use iTunes, because I cannot save anything without buying the high-prized license in the folder already created. I will delete it all and copy from back-ups into a sparse-bundle image that I now create on the mobile drive.

I would appreciate a special offer for students.  
(Version 10.5.1)