Keep stored password in a file?

[user]

Hi,

I want my program has password confirmation to open a menu. The admin of the PC can set the password. Everyone have to enter password to open that menu. Admin and guest can change the password as long as they know the current password. I want to store the encrypted password in a key file.

What happen if guest delete the key file? What happen if guest replace the key file with the original key file (contain empty password)? The effect is my program will have empty password

I need some suggestions here about the concept / scheme about my questions.

Thanks.