Q: iPod Shuffle(2nd gen) mounts to desk top and appears in finder - it does not appear in iTunes12 - when I click on iPod shuffle icon on desktop it gives me the same info as if I click on finder-Worked find last week -How can I restore if not in Itunes

IPod Shuffle 2nd Gen Shows in finder, Icon mounts to desktop, does not appear in iTunes and no device is shown, When I click on the desktop icon I get the same info as if I clicked on finder. Apparently there is nothing on the iPod. Battery is charged and green light appears. How do I restore if I can't access it?