Have you tried accessing the "Administrator" user account? On most occasions, people tend to leave the password empty or even forget to put a password for this account altogether. If you haven't done so already, you can check if the "Administrator" account is accessible by hitting Ctrl+Alt+Delete on the Welcome/Login Screen and entering "administrator" as the login user then press enter. If that doesn't log you in, than you are out of luck. If you are able to get in however, you may continue by accessing ms-dos by going to start->run and type cmd then press enter. In command prompt, type in "net user username *" without the quotations to reset the password of the username you wish to log into. Now you can access the computer again with whatever programs that was pre-installed available for you to use.