Currently Being ModeratedJul 20, 2012 11:53 PM (in response to wildandfreelance)
Firstly, make sure that your device is not hidden (left hand pane). If it just reads device then toggle between SHOW and HIDE.
Secondly, try all the other ports on your computer, even a number of times.
Thirdly, if you have another computer try plugging your device into it without taking any action, give it a moment, remove it and try it back in your other computer again.
And failing all that put the device into Recovery mode. See here and note the paragraph 'If you restore from a different computer.... ' down near the bottom of the page -