“Music” can’t be modified or deleted because it’s required by OS*X.

[[ when I try to restore the "Music" folder, my computer gives me an error message "“Music” can’t be modified or deleted because it’s required by OS*X." ]]

You can't copy the folders (at the top level) inside your home folder (they exist as "more than" just folders, but as [I believe] "symbolic links".

However, you CAN copy the items INSIDE these folders from one folder to another.

Try this procedure:

You need to open your home folder, then open the "music" folder inside it -- even if there is nothing inside the music folder. Move it to the left on your desktop.

Now, you have to get the backup "music" folder mounted in the finder and visible. Open it so that you can see "everything inside". Move that to the right on the desktop so that both open folders are visible.

Now go to the edit menu and choose "select all" (or type command-A).
This should select everything inside the backup music folder.

Now, carefully "drag and drop" all the selected items into the original [empty] "music" folder.

Do the items get copied over now?

Note: when you restart iTunes, you may have to "direct it" to the music folder again.