You need to make some kind of boot disc to find or remove password. These usually come as an iso file for which you use imgburn to make a bootable disc, the popular tool is Windows Password Key.
The password reset process can be done as following:
Log in any available computer and download Windows Password Key. Install it and burn it to a blank CD or USB flash drive.
Insert the newly made disk to your locked computer, and make the computer boot from your disk, then follow the instructive to reset the password in minutes.