Night hawk say it doesn’t have an Ethernet connected

I bought my nighthawk RAX50 about a week ago and it was perfectly fine. Until now. It was storming out and I figure my internet went out but it was actually the router itself. I have a modem in another room where I run a Ethernet cable to my nighthawk where then I run other Ethernet a to my PC. But when I go into the router settings it says no Ethernet cable is plugged in. I have unplugged it and everything but nothing has happened.