1). Connect your iPod to your computer. If it is set to update automatically you'll get a message that it is linked to a different library and asking if you want to link to this one and replace all your songs etc, press
"Cancel". Pressing "Erase and Sync" will irretrievably remove all the songs from your iPod.
2). When your iPod appears in the iTunes source list change the update setting to manual, that will let you use your iPod without the risk of accidentally erasing it. You can continue to use your iPod and add to it by dragging and dropping content from iTunes: Managing content manually on iPod and iPhone
If you wish you can stop there and just keep using your iPod in manual mode. However, once you are safely connected there are a few things you can do to restore your iTunes from the iPod.
3). If you only want to copy your purchases to the computer that can be done using iTunes, you'll find details in this article: Copying iTunes Store purchases from your iPod or iPhone to a computer
For everything else (including purchases) there are a number of third party utilities that you can use to retrieve the music files and playlists from your iPod. You'll find that they have varying degrees of functionality and some will transfer movies, videos, photos, podcasts and games as well. You can read reviews and comparisons of some of them here:
Wired News - Rescue Your Stranded Tunes
Comparison of iPod managers
A selection of iPod to iTunes utilities:
TuneJack Windows Only (iPhone and iPod Touch compatible)
SharePod Windows Only (iPhone and iPod Touch compatible)
iPod2PC Windows Only
iDump Windows Only
YamiPod Mac and Windows
iPod Music Liberator Mac & Windows
Floola Mac & Windows
iPodRip Mac & Windows (iPhone and iPod Touch compatible)
iPod Music Liberator Mac & Windows (iPhone and iPod Touch compatible)
Music Rescue Mac & Windows (iPhone and iPod Touch compatible)
iGadget Mac & Windows (iPhone and iPod Touch compatible)
iRepo Mac & Windows (iPhone and iPod Touch compatible)
iPod Access Mac & Windows (iPhone and iPod Touch compatible)
TouchCopy Mac & Windows (iPhone and iPod Touch compatible)
There's also a manual method of copying songs from your iPod to a Mac or PC. The procedure is a bit involved and won't recover playlists but if you're interested it's available on page 2 at this link: Copying Content from your iPod to your Computer - The Definitive Guide
4). Whichever of these retrieval methods you choose, keep your iPod in manual mode until you have reloaded your iTunes and you are happy with your playlists etc then it will be safe to return it auto-sync.
2). When your iPod appears in the iTunes source list change the update setting to manual, that will let you use your iPod without the risk of accidentally erasing it. You can continue to use your iPod and add to it by dragging and dropping content from iTunes: Managing content manually on iPod and iPhone
If you wish you can stop there and just keep using your iPod in manual mode. However, once you are safely connected there are a few things you can do to restore your iTunes from the iPod.
3). If you only want to copy your purchases to the computer that can be done using iTunes, you'll find details in this article: Copying iTunes Store purchases from your iPod or iPhone to a computer
For everything else (including purchases) there are a number of third party utilities that you can use to retrieve the music files and playlists from your iPod. You'll find that they have varying degrees of functionality and some will transfer movies, videos, photos, podcasts and games as well. You can read reviews and comparisons of some of them here:
Wired News - Rescue Your Stranded Tunes
Comparison of iPod managers
A selection of iPod to iTunes utilities:
TuneJack Windows Only (iPhone and iPod Touch compatible)
SharePod Windows Only (iPhone and iPod Touch compatible)
iPod2PC Windows Only
iDump Windows Only
YamiPod Mac and Windows
iPod Music Liberator Mac & Windows
Floola Mac & Windows
iPodRip Mac & Windows (iPhone and iPod Touch compatible)
iPod Music Liberator Mac & Windows (iPhone and iPod Touch compatible)
Music Rescue Mac & Windows (iPhone and iPod Touch compatible)
iGadget Mac & Windows (iPhone and iPod Touch compatible)
iRepo Mac & Windows (iPhone and iPod Touch compatible)
iPod Access Mac & Windows (iPhone and iPod Touch compatible)
TouchCopy Mac & Windows (iPhone and iPod Touch compatible)
There's also a manual method of copying songs from your iPod to a Mac or PC. The procedure is a bit involved and won't recover playlists but if you're interested it's available on page 2 at this link: Copying Content from your iPod to your Computer - The Definitive Guide
4). Whichever of these retrieval methods you choose, keep your iPod in manual mode until you have reloaded your iTunes and you are happy with your playlists etc then it will be safe to return it auto-sync.