In case your Chromecast is not responsive in software settings, there is a physical reset button on the Chromecast dongle itself. When the Chromecast has been plugged into power, and your TV finds the little button on the side or the back of the device, press and hold that button. In most of the models, a factory reset will be initiated by holding approximately 25 seconds until the LED turns green and begins to blink. The LED will flash and then stabilize. At this point, release the button, and then the device will reset back to the TV screen, which will briefly show a black screen before displaying the first setup screen. This way, you can reset the Chromecast.