When the progress bar completes, open the Terminal app, which is in the Utilities folder of your Applications folder.
The partial command you typed will automatically be completed to this: resetpassword Press return. Drag folders containing songs to iTunes to add the songs to iTunes again.
This can happen when a library is moved between computers or accessed by a different account on the same computer. Select your startup volume "Macintosh HD," unless you gave it a different name if not already selected. Tip: When you drag files to the iTunes window, you can temporarily reverse the tick box setting by holding down the Alt key while you drag.
You can change this setting so that files are added to your iTunes library without being added to the iTunes folder. A Terminal window will open.