|at the logon screen, press ctrl+alt+del twice (unless the welcome screen is disabled), to show up a window with username and password fields. in the username field, type down "Administrator", and leave the password field blank. click ok to login the administrator account. click start, then run, and put in|
"rundll32 netplwiz.dll,UsersRunDll" and click ok. highlight your username, and click "Reset Password"