If it's a newer model, a laptop can be tricky. If it has a security chip on the motherboard (which it probably does), you can forget about it. You have to physically remove the security chip or contact the manufacturer for back door password. These safeguards discourage theft of the devices... hmmmmm.
When you contact the manufacturer, they will want registration information... did you lose that too?
[edit] What do you think lynlynch: Should we tell him about the LynDoor™ Industries Crack-'Em-All Password Generator?