lost password to home computer

Hello , my name is Danyelle I can not remember the password to open up my desktop. I had taken it from my bedroom to the downstairs for the kids to have access. They have been unable to use this computer due to me having forgot the password to unlock it. How do I gain access and is their anyway that I can override this problem . Please help while I do have access to two other computers in the home I want this one for the kids. Any help you can give will be greatly appreciated. Danyelle Starks