I have been learning Ubuntu slowly and have had little problems but no big ones. I would turn it on and use it, no log in, no password. Then I saw the update for Ub 9.10 so I installed it and --Oh Oh! I got a request for user name and password. I entered these and the password was refused. I used the password which I had always used for adding or removing items.
After many fruitless attempts using every password I could find in my pages of notes, I gave up and re-installed the earliier Ubu. The new password I started on this try did not work, so I went back farther and installed a previous edition. This worked Ok, but like the Optimist I am I installed 9.10 again and the result is the same. This is becoming very difficult on my wife who can hear my Com-profanity from the front room.
Has anyone any Idea how to get out of this?? I am ready to install Puppy linux!
Please try to be very basic with you suggestions since I can't even understand any of the questions I read o n this site, know what I mean?

ffRay Muldoon%

I run Ubuntu 9.10 with no problems, so....

The root account is disabled by default on Ubuntu, so the only password you should need to use is your user password which I assume was entered during the login process. I assume you've tried the basics like checking to see if your caps-lock is on and that you're entering the password in the correct case?