It sounds like your Network Interface card is not set up to receive an IP address automatically. It may have been set with a fixed address that is conflicting with an address already given. To test this, switch off all WiFi connected devices and reboot the router (switch it off and on again).
To check the set up you go to the properties for the Adapter, click on TCP/IP 4 and then properties. Tick auto for both IP and DNS.
Just a thought.