Here are the steps for transfer music from ipod to itunes or computer.
Make sure your computer is installed with itunes.
Now connect your ipod to computer via USB cable.
Computer may open itunes and ask you that you want to sync your ipod.
Click on NO
Your ipod is detected as a one of the drive may be as a G: drive on your computer. Open my computer.
You need to unhide file and folder. Here are the steps for windows vista and xp.
In ipod drive you will find a folder called ipod_control. Open ipod_control folder and you will see : 1. calendars 2. contacts 3. ipod_control 4. notes 5. photos
Open the ipod_control folder Then open the music folder > Copy entire folders (it should like these: F00, F01 ...) onto your computer. Paste it to somewhere on desktop. This is the music that you want to transfer from ipod to itunes or computer.
Now sync your ipod with this computer you will not lose any of your music.