It sounds like the computer is failing to get an IP address from the router. The router should give the computer an IP address via the DHCP service.
Either the router has lost its settings or gone into factory reset mode but the last is unlikely as he still has a wireless connection.
Can you access the config page of the router/AP?
If so check all settings.
Try manually setting the IP address of the computer, but to do this you will need to know the IP address range of the router/AP.
If you can try to connect to the router with a network cable instead of the wireless device.
What hardware does he use?