Unless you "Transferred Purchases" to your iTunes or made a backup of your iPod, there is ABSOLUTELY no way to.
If you lose your music after jailbreaking your iPod, first ensure that you have a backup of your music library on iTunes. Connect your iPod to your computer, open iTunes, and select your device. From there, you can choose to sync your music library back to your iPod. If the music is still missing, consider restoring your iPod from the backup you created prior to the jailbreak.
Yes, restoring your iPod will clear all contents on your iPod.
Yes, but you can sync them back
going back to default settings
You need to back up your iPod on your computer before you restore it.
No, restoring an iDevice wipes everything
Restoring an Apple Device takes it back to factory settings so yes, it wipes the device's previous data. Best to back it up before restoring
you can't, but there is this program called iPod rip. but i doubt it works with the new firmwares apple uses on their iPods.
You back it up on itunes, then reload it again
Yes, restoring your iPod will take off the jailbreak, and you will have to jailbreak it again.
Of course...by restoring the ipod.