I had to do that a few months ago, fortunately, one of the IT guys at my office was able to do it for me, but there are still some features I have no idea how to use.
I can surely sympathize. After the local blackout this past weekend, the laptop that my daughter uses for her OT/PT online sessions hasn't worked properly (skipping and freezing). Yesterday, a friend happened to be here as we (the therapist and I) were trying to figure it out. The friend suggests that we need to reboot the modem. OK, so I let her do that. When the system came back on line, everything seemed fine.
Today, while she was online with her therapist, the same thing was happening (skipping and freezing). Remembering how well rebooting the modem worked, I tried that. But the modem did not come back on. I could get none of the lights on the modem or the router. Without my friend, the therapist and I did not know what else to do. The last resort was to call the internet supplier. After about three minutes of questions, he asks me to check the power cord in the back of the modem. Guess what... Yes, that's right, the power cord had fallen out.