Click on the appropriate tab at the top of the "Recover Account Sign In Information" page, then complete the form.
Click the "Enter" button, and you will see the following message:
You should receive a message like this in the email account that is associated to your account:
If you indicated you had forgotten your username, it would simply be included in the text of the email message.
Click on the link provided, and you will be brought to a screen allowing you to specify a new password:
Once your password has been updated you will be signed in.