Press and hold the reset button for 10 sec. it will restart and check after 5 min. if you are getting new wifi siganl.
if not
connect a network cable to the router ( LAN Port), and the other end to the laptop.
check if the laptop is connected to LAN, if not the router is defective.
if yes open the command (CMD or terminal) in your laptop and type ipconfig /all and press the enter key
it will give the ip address and gate way
enter the gateway ip address in the browser and check if you can access the router configuration page.
login to the site and configure the wifi.