i downloaded apple iOS 4.2 software and now all my songs i purchased on my ipod are

[optimusprime12]

now gone? it's only he ones i bought on my ipod that are gone. i uploaded it to my library but i have like 100 songs i have on my ipod that wont show up on my ipod or my library. idk what to do and i dont know if calling apple tech support will help cuz i think they'll just say i'm out of luck