"When I power off my lumia 535 it reboots with a gear and bolt sign"に関する回答No need to worry! Here we will help you, here are few steps given: 1.Press the volume buttons at the side of the phone to activate the sound panel. 2. Select the v button 3. Adjust sound to the required level 4. Turn Vibrate on/off If it works.. that’s good otherwise there are so many reason to be no ringing, first may be it’s water damage problem or second may be it’s fell down on the floor. Because such phones are very sensitive.