I'm making an assumption that iTunes was working before on the other computer, and now that you have switched computers, the Nano is not being recognized by iTunes?
Try this, from Apple's website:
Learn how to restore iPod, iPod classic, iPod mini, and iPod nano to factory settings.
If you need to restore an iPod shuffle, click here
It is important to understand the difference between "update" and
"restore". Update simply installs the software that controls iPod and
does not affect the songs and files stored on iPod's disk. Restore
erases the iPod's disk and restores iPod to its original factory
because Restore erases all of the songs
and files on iPod, make sure to back up any files you've saved on the
iPod disk. All of your songs, videos, podcasts, audiobooks, and games
can be loaded back to your iPod provided that you have them stored in
your iTunes Library. If you use the Nike + iPod Sport Kit, see this document
for more information.
iPod, iPod mini, iPod nano, iPod classic
How to restore iPod
- Ensure that you have an active Internet connection as new
versions of iTunes and iPod Software may need to be downloaded to your
- Download and install the latest version of iTunes if you do not already have it installed.
- Open iTunes, and then connect your iPod to your computer using the USB or FireWire cable that came with your iPod.
- After a few moments, your iPod will appear in the Source panel in iTunes.
- Select your iPod in the Source panel and you will see information about your iPod appear in the Summary tab of the main iTunes windows.
the Restore button. You will be prompted with one or more restore
options that may prompt iTunes to automatically download the latest
iPod Software. The 4 possible restore options are:
- Restore Option 1: Restore - Restores with same iPod Software version already on iPod.
- Restore Option 2: Use Same Version - Restores with same iPod Software version already on iPod even though a newer version is available.
- Restore Option 3: Use Newest Version - Restores with the latest iPod Software available.
- Restore Option 4: Restore and Update - Restores with the latest iPod Software available.
- If you are using a Mac, a message will appear prompting you to enter an administrator’s name and password.