Not 100% sure bout this, but this site is linked to curse, as is gw2guru. So for new members it is possible to have one login for both sides. Older members who made their account before this site was transfered to Curse, can have a different login for this website. I don't know if this is still possible.
However, you could login here, so if your accounddetails here aren't working there it must be something else. So just try to login, click forget password, enter your emailadres (try different ones if you have more) and let them reset your password. if the emailadress is wrong, it will say it doesn't recognise it. If it is right you will get an email with your new password and a reminder of your curse ID.