How to change the password using the limited account?

I have this computer that my parents never go on anymore and so I use the administrator account. One day I decided to change the password. A week later I forgot the password. How do I change it if I can't go on the administrator account??
How to change the password using the limited account?
Go into safe mode and change it from there. You can get into safe mode by pressing f8 (could be different for yours) at the POST (as it starts up). It should tell you towards the bottom what to press.