erase and restore
If I erase and restore my iPod touch, will everything still be on it?
iPod touch
If you erase your iPod and after that restore the data you previously backed up using iTunes or iCloud, you won't lose anything.
Sync your iPhone, iPad, and iPod with iTunes using USB - Apple Support
Transfer content from an iPhone, iPad, or iPod touch to a new device - Apple Support
However, if you don't have a backup, you will lose the data from your device. Before restoring, create a backup copy of your iPod as shown in the instructions above.