some laptops have hdd and bios passwords.
it a pain in the arse to do but here you go.
unplug it. take the laptop apart. take out the hdd, put it in another machine (laptop) and use power max to wipe it (don't use windows tools). format it as ntfs if you can
back to the laptop. take the ram and regular battery out. take the cmos battery out. touch the negative wire and the positive of the cmos to something metal like a safety pin. now if the capacitor is wired in series this won't work, but most are wire in parellel. push the power button. it won't come on but it will clear the cmos.
put both batteries back in (but no ram). turn it on. it will beep but won't start. repeat this to be sure. this will clear the ram memory. put that hdd back in. reinstall windows.
you have to do it exactly like his or it won't work because the hard drive, ram and cmos all remember that it has a password so you have to clear all 3. it you don't clear all 3, one of them will always restore the other's memory to the password