In case you lose your Internet connection, it is always worth it trying to reconfigure the modem. I did not put it much faith, but it is actually something that is very likely to work. Every modem has a sort of IP address. You will find that in the manual or on the modem itself. NBN modems, for instance, could have that information on a label inside of the gap. You get those numbers and dots and type them inside of your address bar. That should give you access to the modem page. Now, you probably just have to enter your username/login and password for the provider. Even if the led for the Internet is off, this solution might work. Just give it a go before trying to, for instance, reinstall the operational system or reformat your computer.