You'll know Bluetooth is on when the icon is white with a blue background.
You'll know Bluetooth is off when the icon is black with a gray background. Use your finger to tap the Bluetooth icon, which looks like a 'B' made of triangles.Use your finger to swipe up from the bottom of your screen to open Control Center.You'll the Bluetooth is on when the switch turns green. Tap the switch again to turn Bluetooth back on.You'll know Bluetooth is off when the switch is gray. Use your finger to tap the green switch next to Bluetooth to turn it off.
There are three ways to turn Bluetooth off and back on: With The Settings App