Sign into Yahoo: with Facebook, with Google
Yahoo previously allowed users to login to their Yahoo account with their Facebook or Google account and recover it. This feature may no longer be possible, but this article has been kept in case the method still works.
How to log into Yahoo with a Facebook or Gmail account?
Head to Yahoo's Sign-in Helper, and enter your Google or Facebook ID into the Yahoo ID field. Then, click Submit. You may be prompted to enter a CAPTCHA code as an added security measure.
You will receive a password reset email at the ID entered on the sign-in page. Follow the link in the password reset email to create a new password.
You can sign in to your account by simply entering your non-Yahoo email address into the Yahoo ID field when logging in with your new password.
Once logged in, you will be able to upgrade your login ID to a Yahoo account by signing in to Yahoo Mail using your Facebook or Google ID.