logged out but cannot log back in

[Lenny]

Hi,
Since I could not find a set of menus in Ubuntu 12.04, to log out, I pressed 
control + alt + del, and that worked.
I went into session options, and there was the Ubuntu-2D, so I go into that, 
but I cannot get back to the desktop, the only other option is password, but 
I have tried a blank, I have tried typing in ubuntu, and I don't know what 
else to do.
This is a live session on a USB drive.
Glenn