I just found this by googling, but it sounds complicated to me, personally I would format and reinstall, or return to factory settings, if you have this option.
http://www.bleepingcomputer.com/forums/topic20 9153.htm
Can you get into windows ok, to back up anything you want to keep?
Newer laptops can normally be restored to factory settings by tapping one of the F keys, maybe F10 or F11.
Otherwise you may have a windows disc, which you use to format and reinstall.
What make and model is your laptop? Is your os xp or vista?