Restoring deleted iTunes 12 user music libraries After having updated iTunes, my entire music library disappeared. What can I do to restore it?
When iTunes updated, whether automatically or under your permission, it replaced its data which contained information on getting your music. None of the music that you have downloaded via iTunes, or even added into iTunes from a CD won't appear. What only appears is links to stream anything that has been purchased from iTunes, even though it may still exist on your computer.

To fix this, do the following:


Navigate to your computer's music folder.

This is normally the folder called "Music". On Mac OS X computers, you can type this in Terminal:

open music


This should open your music folder. 


Navigate to the iTunes folder

In the music folder, you should see an "iTunes" folder, which has a few files. Locate the iTunes Library.itl file. Rename it to iTunes Library (corrupt).itl.


Locate the missing user library

Next, there should be a folder called Previous iTunes Libraries. Inside this folder, should be a few files, which are called iTunes Library followed by the date. Choose the latest file (The order is Year-Month-Day. e.g. 2015-08-18 for August 18th 2015). Copy the file.


Place the user library back to its proper spot

Now that you've copied the iTunes library that holds all the information about your real music libraries, we need to place it back where it belongs. Go back to the folder where you renamed a file to iTunes Library (corrupt).itl. Paste the copied library here, and rename it to iTunes Library.itl.



Restart iTunes and Voila!

Restart iTunes, and your original music libraries should be there! Happy Listening!