Are you an iPhone or an Android user?
If you had an iPhone and replaced it with another iPhone and you had enabled third-party account backup in Duo Mobile on your old phone before it was stolen then you could restore your accounts in Duo Mobile from iCloud.
Similarly, if you’re an Android user and replaced your phone with another Android phone, and you previously enabled Duo Mobile account backup to Google Drive with a recovery password you can restore those accounts on the new phone from the Google Drive backup, provided you have your recovery password.
If you don’t have a Duo Mobile backup in iCloud or Google Drive that included third-party accounts available I’m afraid we can’t help you restore the accounts. We also can’t recover or reset an Android backup password because we never received the password you set in the first place.
What do I do if I’m locked out of Instagram, Facebook, or another third-party Duo Mobile account?
When you set up two-factor authentication in Facebook you were offered a set of recovery codes. Did you save those? If so, you can use a Facebook recovery code to log in and then go reset your Facebook two-factor authenticator app to delete the old phone.
If you added your phone number to Facebook for SMS authentication you could have a login code texted to you.
If you didn’t save the recovery codes from Facebook either and don’t have your phone number added for SMS then you do need to work through account recovery with Facebook.
Duo doesn’t have access to your Facebook account nor is there anything on our side we could enable/disable to let you log into Facebook as the Facebook authentication configuration is entirely stored within Facebook.
I hope Facebook support is able to help you soon.
