How do you unauthorized a computer for itunes?

How can I get my ipod to be detected by Itunes and my computer?

• A few days ago when I plugged my Ipod to my computer, an update was available for my ipod, I clicked it. Once it was about to be done an error window popped up, I don't remember what it said, there was an error number but i cant remember it. After I X-ed the error window, I noticed my ipod was not being detected by Itunes, so i unplugged it and plugged it back in. IT DIDNT WORK :( Now everytime I try to plug my ipod, my laptop makes that noise it makes when you plug something in, but I go to computer and check for the device nothing shows up, and Itunes doesn't detect it either. Also, when I try to turn on my ipod,or when i plug it in, the Itunes logo shows in the screen and it tells me to plug it in the computer, I have no idea what I should do. I already went to the Itunes page and try to solve it with their help. Dont tell me to restart my ipod, or to reinstall itunes, cause I already did, I did a lot of stuff. My Ipod is a fourth generation, and I use Windows 7.

• Answer:

  First try plugging into itunes hold both buttons until screen turns black. Once screen turns black hold the home button until a message about recovery mode appears in itunes. (If screen does not remain black start over)If that does not work, try going device manager and reinstalling the driver for your ipod.