Look on the back of router. There should be a small hole, usually just to the
left of the power jack on router. Inside that hole is a small button. Find
something small enough to press and hold it while the router is powered up.
While pressing and holding, watch the lights on the front. With router, its
usually the M1 and M2 lights that will go solid while holding the reset
button. Keep holding the reset until they start blinking. Its now reset.