As a matter of fact, when you can't import music from iTools to iPhone, you can use Tenorshare iPhone Care pro to do that. It is a software program developed by Tenorshare. Relative to the overall usage of users who have this installed on their PCs, most are running Windows 7, Windows 8.1 and Windows 10. While about 51% of users of iPhone Care Pro come from the United States, it is also popular in United Kingdom and Romani. Now you can see how to use iPhone Care Pro to deal with your problem.
Step 1: Download iPhone Care Pro from HERE and then install it to your computer. And then connect your iPhone to the computer with USB cable and start the program.
Step 2: Click on “Files Manager” in the main interface and select red icon “Music” to click. Click “Add” on the menu to add music to your iPhone.
Step3. Click "Refresh" and all the changes will be synced with your iOS devices. During the sync progress, iPhone Care Pro will recover your missing or corrupted iTunes Media files.