iPod Recovering songs

[lilheed]

i have a 5th gen iPod that i can't get to charge no matter what i try. so i bought a portable hard drive storage system to just plug the iPod hard drive into and you plug the usb port into my mac. when i pull it up in disk utility though it doesn't recognize it. It says "The disk you inserted was not readable by this computer" and when i click initialize and try to verify the disk it says it needs to be repaired. so then i go to repair it and it won't work. it says to back up all files and reformat the disk. the iPod was last used on a pc so i don't know if that is a problem. all i want is to get the music off of the hard drive. if anyone could help i would greatly appreciate it