iTunes Library all songs deleted

You can use a keyboard command to prevent your iPod auto-syncing with iTunes. While connecting the iPod to the computer on Windows hold down the Shift + Ctrl keys (on a Mac hold down the Option and Command (⌥ and ⌘) keys). This will stop the iPod from auto-syncing with iTunes and the iPod will appear in the source list. Wait until you are sure the iPod has mounted, and that it will not auto sync and then you can let the keys go. This may take between 20 to 30 seconds depending on your computer. Your iPod should appear in the iTunes source list from where you can change the update setting to manual and use your iPod without the risk of accidentally erasing it. In iTunes 7 Check the "manually manage music and videos" box in Summary then press the Apply button. Don't uncheck Sync Music it will be unchecked by default when you choose the manual setting: Managing content manually on iPod

If you want to recover your songs there is a manual method of accessing the iPod's hard drive and copying songs back to iTunes on Windows posted in this thread: MacMuse - iPod to iTunes

If you prefer something more automated then there are a number of third party utilities that you can use to retrieve the music files and playlists from your iPod, this is just a selection. Have a look at the web pages and documentation for these, they are generally quite straightforward. As iTunes 7 is just out some of these may not have caught up with it yet though I haven't experienced any problems with the Mac software I use.

YamiPod Mac and Windows Versions
iGadget Windows Only
iPodCopy Mac and Windows Versions
iPod Access Mac and Windows Versions
PodUtil Mac and Windows Versions
iPodCopy Mac and Windows Versions
PodPlayer Windows Only
CopyPod Windows Only

There is a new function in iTunes 7 under File, "Transfer Purchases from iPod" which transfers iTMS purchases. A paragraph on it has been added to this article: How to use your iPod to move your music to a new computer

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 again.

If at any point using the keyboard shortcut you do get a message that your iPod is linked to a different library and asking if you want to link to this one and replace all your songs etc, press *No* (or "Cancel" if you are using iTunes 7).

Follow the instructions in the MacMuse link if you want to copy them manually. Alternatively download a utility from one of the links to their web pages.