How to reset Dell Inspiron 1525 to factory settings??

Hello, I know it's 2014 but im still very new to technology.
So this is my mother's laptop, it has viruses, and a so called "friend" said they know all about it and can help her. Idk what they did but basically they didn't solve the problem and it runs worse now. I found that you're supposed to be able to reset this laptop by restarting it and pressing f8. However once I get to the screen that allows the factory reset, it asks for the administrative password which is unknown. Is there any other way to restore this laptop? Any help would be greatly appreciated!