There should be a small pinhole on the back of the router with a recessed button, usually red and usually labeled "reset". Press and hol;d that button for at least 15 secondes, possibly as long as 30 seconds and the router will reset to tfactory state. You will then need to connect a computer to the router by ethernet cable and go through the first time setup again. During the setup you will be able to turn on WiFi, name your connection, and set up encryption. Don't use WEP. At this point you should be using WPA/WPA2 Personal.