At the site you have the option of either changing or resetting your password.  Here is the difference.

You change your password when you KNOW your current password.

You reset your password when you DON'T KNOW your current password, but HAVE created a password profile. You also can add a personal email on file, so you can choose to use email verification to reset your password. Here are instructions on how to add a personal email to be used for password verification.

If you haven't created a password profile, don't know your current password, and haven't added a personal email, you can contact IT by emailing or calling 617-349-8770, and pressing option 2.