To start, go to the Pantone API login page: Pantone API Login
Click on: Forgot your password?
Enter the email address you used to sign up for Pantone API
Check your email for verification code and type in a new password. Once entered, click Change Password
This will bring you back to the main login page where you can test that your login is valid.
If your password is incorrect, you will get the following screen.
To test your new password, you can go to the Testing The Pantone API page that has a link where you can login to verify access.