To reset your password with your T-Mobile account, use the reset password page on T-Mobile.com, as of July 2015. You can verify your identity by text message, email or security questions. Once you've verified yourself, you can set up a new password.
Visit the T-Mobile.com home page, and place the cursor over My in the upper right corner. Click on Login. Click on Forgot your password, then enter your phone number and either your billing ZIP code or your T-Mobile PIN. Once you enter the information correctly, you can choose your verification method.
If you select the text message option and click Next, you receive a code to your phone via text message. You can enter it online to verify your identity. If you select the email option, you receive an email with a link to click on to reset your password. If you select security questions, you must correctly answer security questions you previously set up with T-Mobile to verify your identity.
The password you create must meet T-Mobile's requirements. After you save your new password, you're automatically logged in to your account.
If too many login attempts are made with an incorrect password, T-Mobile may lock your account. The process for unlocking the account is the same as that for resetting your password.