classic windows logon - forgotten password

I had a friend change my user account from using the
Welcome Screen to the more secure Classic Logon Prompt. I
applied the changes, and choose to restart the machine.
When I did, the password was not what I had thought it
was, so I cannot get passed the screen.

How do I reset the password? How do I get my access to my
computer back? It is a stand alone laptop, with no
network connection.

Thanks,
Nathan