Windows systems come, by default, with an administrator account. If you don't know your administrator password, you should. This password is a great fail safe to have around if you should lose or forget the password for your user account. Beyond that, however, it's generally good security practice to use the administrator account to install software and to use a restricted account for day-to-day computing. If you don't know your computers administrator password, it's possible to get it.
Make sure there actually is an administrator password by trying to log in as the administrator. Start your computer and wait for the Welcome screen—the place where you select which user to log in as—and press "Ctl," "Alt" and "Delete" at the same time. This will bring up the old-style login box, where you can type a user name instead of clicking one. Type "Administrator" as the user name and press "Enter." If you this logs you in, congratulations; you're logged in as administrator.
Find the administrator password the easy way. If someone you know set up your computer, they may know the administrator account; call them and ask for it. If not, don't worry; you can crack the Administrator password.
Download the Ophcrack Live CD (for free download, see Resources). The download will come in the form of an ISO file.
Burn the Live CD to a blank CD. If you don't have software that can burn ISO files, check out ISO Recorder (for free download, see Resources). This free program is capable of burning ISO files to disc. Once ISO Recorder is installed, burning the ISO to disc is as easy as right-clicking the ISO file in Windows Explorer, then clicking "Burn Image to Disc."
Insert your CD and restart your computer. Be sure to boot from the CD—in most cases this should be automatic. If it's not automatic for you, be sure to press the button for on-screen instructions right after powering on; often this button is "F2." The computer say will enter boot mode.
The Live CD will boot and automatically run Ophcrack. Click on the "Administrator" account, then click "Crack." Wait a little while and Ophcrack will reveal your password.