Better you take off your hard disk and connect it to some other system as a slave. You can access the data from there and can take the backup..
Further you can search more on REGEDIT to disable the administrator password.
Repair install your operating system. Do not format, and overwrite the windows files. You will have a new registry, so some applications will not work, but you still have all of your files.
Build a boot CD like UBCD4Win (Ultimate Boot CD for Windows) and use it to access the data you need to access.
There are other password change utilities that require you to have physical access to the machine like CHNTPW
Unfortunately, you have to remember if what are the possible word combination for your password. This is because it is almost impossible to recover your data or even open your account.