Earphones won't connect to any of my devices.

I heard that you connect first with one and the other one with side button connects to the other Bluetooth headpiece.

On main menu screen swipe down from the top and you will see
Wireless press left arrow and you will see a menu with blue tooth listed .turn on and opair headphones.

If they are Bluetooth earphones, you simply pair them together. On the earphones, to put them in pairing mode, you usually press and hold on button for 5 seconds. Then put iphone into Bluetooth discovery mode. Settings>bluetooth. The device will show up, then click to pair. If it ask for a code, it is usually a default of 0000.

1) Check to be sure that "Hands Free" mode is off. This may be overriding the settings to believe you have bluetooth connected. and/or
2) check to be sure a bluetooth device the phone is paired with is not on and active.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/steven_7f54ab9063554f66

Its very rare a mac has sound problems. Some earphones consume batteries, does yours have batteries in it? and is it powered on while connecting? With the earphones connected, check system volume and increase the sound while playing music. If there is sound coming from the mac itself then there maybe an issue with the AUX connection. Possible dust blocking the port. Clean it and try again. If there is no sound coming from the mac itself while the earphones are connected, then the AUX port is connected to the earphones and is in good working condition. Increase the volume on both devices, the mac and the earphones, if it has this feature. If there is still no sound, there may be a problem with the earphones itself. Possibly bad wires already, connect the earphones to other devices and listen for sound. If still no sound, replace earphones.

Did you try putting this:
here:

hello, i have a philips wireless head set and this how i set mine up, i take it you've got the sensor with long black wire attach to it this plugs into your earphone socket on your tv set then plug the power adaptor the sensor switch on make sure the sensor pointing towards you and put the batterys into the earphones and switch earphones on you should have sound get back to if you have trouble thanks

regards
shaun

Hi, I hope you've solved the problem.  But if the first solution does not work for you maybe this one will.

I looked at the specs for your monitor. LINE IN is for plugging in a device that makes sound, so this is not the right hole (called a jack) for the headphones plug.  Look on the back of your computer for a hole that is outlined with light green.  You wrote that you removed " the audio wire that connects the monitor to the CPU", this would be the place to plug in the headphones.  

Make sure that the headphone plug is plugged in as far as possible. There's an issue of it seeming like it's connected, but it still needs to be pushed in a little more for a full connection.

Try unplugging the earphones, turn on and then reconnect the earphones - worked for mine.