iTunes won't recognize iPod nano

Here's the problem. I plugged my iPod nano into my Mac to sync, but iTunes did not recognize it. Realizing I couldn't eject the ipod w/o it being recognized, I impulsively unplugged it from the ISB connector. Now when I plug in the ipod in order to sync, iTunes tells me the device wasn't properly ejected. It says that the next time I plug in the ipod, iTunes will repair it; however, after multiple restarts of both the computer and iTunes, there is no indication that repair is going on. I have reset the ipod several times. Nothing is having any effect. What should I do?