then the following do these following steps in your hand set one by one and check
1. Unpair all Bluetooth devices which were connected earlier (Scroll down notification panel > Setting > Connections > Bluetooth > Turn on Bluetooth > Tap the settings icon next to the Bluetooth device > Unpair).
Again turn on Bluetooth> Scan> Tap on the Bluetooth device
If not worked then
2. Go to the settings>>apps>>Bluetooth>>storage>> clear cache.
After even not worked then
3. Reset network settings (Scroll down notification panel >Settings>General Management>Reset >Reset network settings)