Is there anyway at all that I could break the internet connection for all my devices of my home network remotely from my Windows PC? I don't necessarily mean a proper way to break it, but any method that results in no one in my house having a connection. I get to reset my router and modem all the time, so obviously my ISP knows how to do it, so why cant I?
You can, turn on remote management in your router (almost all of them have it):
Then click disconnect:
Note that doing this will make your router inaccessible. Your ISP can do this because they control your account at the source and can unplug you completely.
You claim you do not have the password, the only way to really limit their internet remotely is to perform a denial of service, which I believe is illegal anyways. Your ISP has complete control over your connection to their backbone, hence why they can cut you off if you don't pay the bill. You don't have this kind of access so it is not possible.
You also said "you reset your modem and router all the time". Resetting your router should reset the password.
If your router has remote management, you could login to it and tell it to shutdown, but you wouldn't be able to restore it remotely.