If you can’t get your iPhone or iPad paired with your Bluetooth device–or if iOS just isn’t seeing the device at all–the old “turn it off and back on again” advice applies, with a bit of a twist thrown in. Restart Bluetooth using the following steps:
Turn off the Bluetooth device you’re trying to pair.
Turn off Bluetooth on your iOS device from Control Center, or by going to Settings > Bluetooth and turning the “Bluetooth” slider off.
Force restart your iOS device by holding the Home and Power buttons down until you see the Apple logo on your screen. If you’re using the iPhone 7 or 7 Plus, you’ll hold down the power and volume down buttons instead.
When your iOS device has restarted, turn Bluetooth back on.
Turn your Bluetooth device back on and try pairing it with your phone.
Most of the time, this technique should solve pairing difficulties.