Ask Max: New iPod erased all my iTunes songs, what gives?
When I plugged the new iPod into my computer, I found that a good majority of the songs I had saved in my iTunes had disappeared. How can I get those songs back?
In most cases, all your music should be safely stored in one iTunes account and regardless of what happens to Apple iPods, all the music is on your computer. In that case you can just re-sync from iTunes to a new iPod and the music will all be on the new Apple iPod, assuming it all fits.
It is possible to setup your iPod to be manually managed and you can add music to your iPod from many sources. In that case you could have half your music in your work computer's iTunes library and the other half in your home computer's iTunes library. If that is the case you will need to ether merge the libraries together or reconnect your iPod to both libraries in a manually managed mode. Here's Apple's instructions on manual iPod & iPhone content management.