How to recover lost songs from iPod Nano 2nd Generation

I was trying to figure out how to transfer the songs from my mom's iPod nano 2nd Generation to my MacBook Pro when it suddenly said it couldn't read the files. I tried recovering it, but it was stuck on the recovery screen, even when I unpluged the iPod. I had to restart my Mac, and when I checked the iPod, hoping nothing changed, all 490+ songs were gone. Is there any way of possibly recovering these songs back onto my iPod/MacBook? And if so, how do you transfer the songs? (If the songs are still on the iPod.)

Thanks.

[Re-Titled by Moderator]