Forgetting password is not a new issue so if you have forgotten your Yahoo password then you can recover it but in order to recover Yahoo Password you have to enter your alternate email id or mobile number if in case you are unable to recover to Yahoo Password then just make a call or drop a message at Yahoo Phone Number  +1-855-479-3999 at any time.

 https://www.mailsupportnumber.com/yahoo-customer-service-number.html