Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Copying Music from iPod
Everyone knows that to copy music from iPod, one needs iTunes to be installed. But what if something happens to your iTunes library and you won’t be able to sync your iPod with it? There’s a way to copy music to your Mac without iTunes.
1. Plug your iPod into your Mac.
2. Hold down the Command and Option keys. As a result of this combination iTunes won’t sync to your iPod.
3. Your iPod will be shown in the Finder sidebar. You won’t be able to instantly view the music files; however, the following Terminal command will make them visible:
defaults write com.apple.Finder AppleShowAllFiles YES
4. Click and hold the Finder icon in the Dock, press the Option key and select Relaunch. The Finder will restart and display all invisible files.