By mistake I disconnected my iPod Classic when it said Do not disconnect. Now it doesn't appear in iTunes, but it does appear on my desktop. How can I get to reappear in iTunes (have tried resetting and rebooting).

Thanks PlanB, the weird thing is that I've since connected the ipod to my old PC laptop and it showed up there, in iTunes, perfectly. But it's still not appearing on my macbook pro's iTunes, where I disconnected it from when it said Do not disconnect. I'm thinking that it might have something to do with the mac now, and am reluctant to reformat it. If anything springs to mind, let me know :-) Thanks!