It is possible that your Account username and password are different than your Game Subscription username and password. For more information about this visit this post.
If you’re unable to log into register.funcom.com, you can use the “Forgot your password?” tool to reset your Account password through the email address registered to your account.
Game Subscription Password
You log into our games using your Subscription username and password. The user name for your subscription can be seen on your account page(register.funcom.com) in the drop down menu in the left-hand menu. Passwords for the subscriptions can be changed through the Password Change option in the left-hand menu.