Really depends on what the error is.
1.) Invalid User-ID, checks for caps, mispalced underscore, etc.
2.) Invalid password, as above.
You should be able to retrieve both by sending your subsribed e-mail address in via the links below the sign-in window.
Sorry, can't help more as an error is to vague to identify the problem. One rason why I hated IT Customer Support, we were asked to identify problems but never given details or accurate info.