Depends: If it was a smartphone; most of them have apps that backup for you in the background. If it was andorid; at least you contacts would be backed up to your gmail account. And there are other apps that sync you other data to the cloud as well. But; I would think you would know if you did that.
If you had a fairly recent ATT feature phone, its asks you if you want to sync your contacts to a cloud address book when you activae it. If you did that your contacts are at least saved.