To fix the issue of Yahoo two-step verification not working, please follow the following steps. log on to https://login.yahoo.com/account/personalinfo Sign in with the username and password and click account security Go to Two-Step Verification and click enable button Enter the mobile number for the code and re-enter the code for confirmation You can also reach the website http://www.referenceitpro.com/blog/yahoo-step-verification-not-working or call the number 1-888-560-1555