If for some strange reason your earphones have disconnected from each other, then we explain how to pair them again (between them).
On your mobile: Remove previous links from; Settings-> Bluetooth -> (delete, forget ...)
Put the headphones in the case.
On your mobile: Turn off the Bluetooth.
Remove the two earphones from the case and double-tap the touch on each headset simultaneously (double tap on both at the same time).
Look at the LEDs of the headphones, after a few seconds, the LEDs of one of the headphones will stop blinking (usually the left) and the other will continue to flash.
On your mobile: At that time, go to Settings-> Bluetooth, search for the earphones and press to connect.