ipod classic 160 usb not recognized

Ipod Classic 160 (not recognized by computer) and under Ipod Diagonistics (no Ipod found). I have two other Ipods which I-Tunes and my computer recognizes. I have reset Ipod to no avail. Because I am unable to connect to I-Tunes with the Ipod I am unable to restore or reset. I have watched all the YouTube videos and followed each. One thing that is strange is it will not test or disconnect from disk mode. I really enjoyed this I pod and hope one of you can resolve this problem for me. Thanks