Need help with my fiance's Iphone 4 and loss of contacts.

My fiance has had issues with her Iphone 4 ever since she upgraded to the new OS. Today the phone went black for a while. When she got it back up all her contacts, messages and calendar were gone. She has her music, photos and apps. What does she need to do to restore her contacts, messages and calendar without losing her music, photos and apps? I ask because when I got my macbook pro and first synced my iphone I screwed up and lost my contacts. I dont want to mess up again. Seems a simple restore from backup should work, can that be done?

thanks

is there a backup on her computer? I'm pretty sure you can restore it from a backup. Might be a little risky if not everything is synced appropriately but just an idea.

Did she turn on iCloud or any other services?