Press the Windows + R key combination, type cmd and click OK. Once the application is opened, type ipconfig and press Enter. Copy the address next to Default Gateway and open your router's configuration page. Enter your router's username and password and find the Network section. If you don't know the username and password, press the Reset button on the router for about 30 seconds. This way you will reset its settings to default. Enter
admin as a username and
password as a password and open the Network/Wireless section. Click the Security option and look for the Password, Passphrase or Shared Key box. Enter your new password in the provided field and click Save or Apply Changes.