use kon-boot avalible here in hirens boot disk
http://www.hirensbootcd.org/files/Hirens.BootCD.14.0.zip. after you download it burn it to a cd using a program like cdburnerxp then restart your computer with the cd in the drive and boot your computer off the cd, after hirens boot cd loads use the up and down arrow keys to select kon-boot then press enter once kon-boot loads press enter it will do some stuff then your computer will boot after you come to the logon screen just select the account you want to logon to and it will logon no password required . oh by the way when you click on the account the password box might appear just leave it blank. then once you logged onto the admin account you can change the password on all the account (since its a admin.)
