Registered my iPhone as a new device and now my old backup is gone in iTunes...

[okayplayer]

Is it stored anywhere on my Mac's drive? The Apple employee said that my contacts were stored in address book, but there's nothing there...

Thanks

 

[-aggie-]

Apple stopped using incremental backups awhile ago. In the future, save your backup to a safe place, so when it gets overwritten,you’ll still have it. It’s in the MobileSync directory.

Your contacts are in Address Book if you synced them to Address Book in iTunes. If you didn’t, start doing that from now on, since there’s no reason not to and just depend on the backup for contacts among other things (like iCal).