DIAGNOSIS Your computer is on a different subnet, or the router's DHCP server/administration service is disabled.
FIX Manually set your computer's IP address. For Windows, go to Network Settings > Change adapter options. Right-click your connection, Properties > IPv4. Set IP to 192.168.1.10, Subnet to 255.255.255.0, Gateway to 192.168.1.1. Open a browser and try 192.168.1.1 again. Use 'admin' for username and your password (default is 'password').
IF THAT DIDN'T WORK The router's IP may have been changed. Use Netgear's Nighthawk app to discover the router's IP if connected via WiFi. Alternatively, open command prompt and type 'ipconfig'. Look for 'Default Gateway' address. Try that IP in your browser.
HEADS UP If you manually set an IP and still get no connection, the router is in a failed state. You must perform a 30-30-30 hard reset via the rear pinhole, which will restore the default IP of 192.168.1.1.