Can’t connect to wifi

Start your troubleshooting here, If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

So, you are saying the device will not connect to any other wi-fi networks either? If that is the case, you need to contact Apple Support. Use the Get Support link at the top of the page, or you can use the Apple Support or Apple Store apps and set up a Genius Bar appointment.