Password issue - can't login to Fedora

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Greetings: I am using Oracle VM to log into Fedora Linux. I've been using it for weeks with no issue. I initially had no password set for my login. I set it a few days ago. Today, the system is saying I'm not using the correct password.

Is there a way to get around this? I've tried logging is as "root" using "password" and "root" as the password (unless I changed it and don't remember), but the system rejects those passwords.

What should I do? Please advise.

Thanks.

AJB