Sorry to hear this! Are you on Xbox or PSN?
First, go to your profile and make sure your gamertag or PSN ID are correct. Remove them and correct as you need.
If you are on Xbox, what can happen is someone is logged in to xbox.com already on your device, and when you authenticate you connect that user to your FTW.in profile. You can fix this by logging out of xbox.com, then remove xbox from your profile and connect again.
If this isn't the issue, let us know. The Bungie API could have been down as well which means we can't retrieve your Guardians. We plan to put in a manual entry if that happens in the future.