To restore your personalized information, just enter your Yahoo! ID and password in the spaces provided either on the Sign-in page or Guest page, and click "Sign In." You don't need to re-register.
When you sign in using your Yahoo! ID and password, your browser can remember this information by setting a cookie. We've provided a checkbox on the Sign-in page so that you won't have to sign in each time you come back. (We may ask you to re-enter your password if you've been away from the computer for too long. By default, the cookie will expire after eight hours.)
If you forgot either your Yahoo! ID and/or password, just click the need help signing in? link on the Guest page.