A friend is having problems with logging in?(10 points for the [first] answer that helps most)?

[kochii02]

That's not a big problem and can easily be solved. Follow these steps:
1. Try to login using last known details.
2. It will show error and than you can locate your account using the email address you used to signup with Facebook.
3. Follow the steps again you described on the above message.

Just one thing you need to confirm before making another try. Is she using same phone number for the two accounts? or different phone number?