You might try to take your iPod and plug it into a different computer than the one you originally tried to update it with. When it is plugged in you should get the same not recognized error. Put it into DFU mode (hold power and home for 10 seconds, then release power) You should continue to have a black screen but iTunes should recognize your iPod, and will open saying you need to restore it. Unplug it from the computer and plug it back into your original computer (make sure iTunes is closed) and it should work fine now being recognized again. Hope this helps, good luck.