Router Not Working, No Lights and No Wi-Fi, Fixed Step by Step
A router that does nothing at all is usually a power or hardware problem, not a settings problem. There is no single error message for this condition, so the fix is a process of elimination: power, cables, the modem, then the router itself.
The fix, in order
Check the power first. Make sure the power adapter is firmly plugged into the router and into a working wall outlet, not a switched-off power strip. Try a different outlet. If the router has a power switch on the back, confirm it is on.
Look at the lights. No lights at all points to power or a dead router. Lights that come on and then go out, or that never settle, point to a boot or firmware problem, see the firmware recovery steps on the router firmware update failed page.
Power cycle properly. Unplug the router and the modem from power, wait a full 60 seconds, plug the modem back in first and wait until its lights settle, then plug the router back in and give it two to three minutes to boot.
Check the cable between modem and router. The Ethernet cable must run from the modem to the router's WAN or Internet port, not a LAN port. Reseat both ends and try a different cable if you have one.
Test with a wired connection. Plug a computer directly into one of the router's LAN ports with an Ethernet cable. If the wired connection works but Wi-Fi does not, the problem is the wireless radio or its settings, not the whole router.
Try a factory reset. With the router powered on, hold the recessed reset button with a pin for about 10 seconds until the lights blink. This erases your Wi-Fi name, password, and custom settings, so only do it if you can set the router up again afterwards.
Do not open the router case. There are no user-serviceable parts inside, and opening it usually voids the warranty and risks damaging the board.
If it still happens
If the router shows no lights on a known-good outlet with a known-good adapter, or if it powers on but never finishes booting after a factory reset, the hardware has most likely failed. If the router was supplied by your internet provider, contact the provider through its official support channel about a replacement. If you bought it yourself, check the warranty with the manufacturer.
Common questions
How do I know if the router is dead or the modem is dead? Plug a computer directly into the modem with an Ethernet cable. If the internet works that way, the modem and the line are fine and the router is the problem. If it does not work, the problem is the modem or the line.
Should I reset or restart first? Restart first. A restart clears temporary glitches and keeps your settings. A factory reset erases everything, so it is a later step, not a first step.
My router worked yesterday and now does nothing. What changed? The usual suspects are a power cut or surge, a failed automatic firmware update overnight, or a power adapter that finally gave out. Check the outlet and adapter before assuming the router itself died.