where do I find the passwords to use?
If you do not have the password, try to recover it by using the lost your password link. Or reset your password by using the method WPyogi gave above.
If that site is hosted with 1and1, you may contact them for assistance with the issue. Can't you?
Whatever action is to be taken to regain your site is based on the credentials you have to claim the site. We do not have any such information.