To verify that you are using the correct login information go to the Classifieds login page, click the button found just below the Login >> button that says "Forgot password? Click here."
In the new window that opens, enter the email address you provided during the registration process and click the 'Send Password' button. Your password and username will be sent to your registered email address.
If you do not receive the email in your Inbox, check your junk/spam folder.