Why can my system not update from iOS 12.5 to another

I have an iPhone 6 it’s hacked I’m certain it will not allow me to update anything nor change the Apple ID nor receive the password change it is frustrating because it seems to be controlled by an outside source that continuously changes the settings. It will not allow downloads. I’m not sure but I believe it has been I guess rooted in the wrong certificates. However, it won’t allow me to reset the phone it keeps saying that I have to have the password but it has been changed and I’m virtually locked out. How do I fix this issue?