Software for desktop and mobile.
Tuner
tuner.exe show locations | findstr file://localhost/
Let's say you've moved your entire music collection from D:\Music to E:\Music. If you run:
tuner.exe show locations
You'll see that the locations now begin with file://localhost/D:/Music, since iTunes® cannot find the files.
To update the location of every track in the library, use the command:
tuner.exe replace file://localhost/D:/Music E:\Musicor
tuner.exe replace D:/Music E:\MusicIn either case, Tuner will remove the file://localhost/ portion, update the matching part of the path, and replace any forward slashes with back slashes.
Since Tuner will ask for confirmation for each and every match, you may want to use the /Y switch:
tuner.exe replace /Y D:/Music E:\Music