Sorry if this question is a duplicate. I searched some hours but could not find any satisfying solution for the following problem.
I am using a two-factor-authentication-app (in my case Google Authenticator) for advanced security. This works well.
But I am afraid: what can I do if I lose my smartphone or my smartphone is broken? How can I restore the access to the several websites/services/etc that require two-factor-authentication-app? Is there any "seed" I can backup (and "import" in the two-factor-authentication-app on my new phone) to restore login-access to all sites/services where I am using two-factor-authentication?
Let's think about the following case:
I am using a two-factor-authentication for login to example.com. Now I have not access to my smartphone anymore and can not disable two-factor-authentication for my example.com-account because I can not login and example.com does not provide alternative login-options. I can not see any possibility to login to example.com.
The issue that someone else may get access to my two-factor-authentication-app is not a part of my question because if my smartphone is stolen the thief does not know my regular password.