Periodically changing your password in Yahoo! e-mail or any other e-mail is a good way to help keep your account secure. In order to protect your account from unauthorised access, Yahoo! e-mail requires certain information to be provided in order to change your password. When you are unable to answer the security questions you chose when setting up your Yahoo! account, you must use alternate methods to be able to change the password.
Go to the Yahoo! "Sign in Problems" page (see Resources) and select the appropriate radio button, then click "Next."
Type in your Yahoo! ID--the portion of your Yahoo! e-mail address that comes before "@yahoo.com." Enter the code shown in the box below where you enter your Yahoo! ID, then click the "Next" button.
Select your birth month from the drop-down menu, choose the country you selected when setting up your Yahoo! e-mail account and enter the postal zip code of the city or town in which you lived at the time your account was created. Leave the zip code box blank if you are certain you didn't enter a zip code when setting up your Yahoo! account. Press the "Next" button.
Click the radio button in front of the alternate e-mail address to which you would like password changing information sent. Yahoo! will list the alternate e-mail addresses you provided when you created the email account. The email address you select must still be accessible.
Use the link or code provided to you in the email Yahoo! sent to your alternate e-mail address to change your password.
Write down e-mail account information and keep in a secure location, such as a home safe. Once you are able to change your password, update your security questions and answers to something you are able to remember easily.