You need to use the online wizard to recover/change your password. If you don't have access to your phone number anymore, there are other ways to recover it. For example, you can use the security questions and their answers to reset the password. In fact, Yahoo relies on this security measure very much. Meaning that if you don't know the answers to the security questions, then the account will be lost for good or until Yahoo disables it permanently or deletes it.
