If tu mean fanpop accounts. They should give tu an option before tu log in via using your correo electrónico to recover accounts o passwords. If not that's basically how tu do it. tu use an correo electrónico and then the site then sends tu your account name and/or contraseña o gives tu an option to change your password.
tu can go to the main fanpop inicial page and there'll be an option on somewhere near the bottom which gives tu the option to contact Fanpop. tu can use this feature correo electrónico them and ask if tu can get your account back. Don't hold your breath though... it's not likely to be recovered.