If you simply want to check whether a new set of headphones and microphone works, find the connectors on your computer (they are often marked with headset and microphone signs) and plug the headphone wire (usually green) into the sound output (headphone sign) and the microphone wire (usually pink) into the input.
Now you can play a sound file on your computer and adjust the volume on your headset. If you hear the sound properly, your headphone is working. Try hearing from the left and right channels separately to ensure both work properly.
To test the microphone, open up the start menu, go to accessories and run the sound recorder application. Click the red button to start recording and speak into the microphone. Stop recording and play it back, if you can hear yourself, your microphone works. Some headsets have a separate switch to turn the microphone on and off, check for that if you are unable to record sound.
If your existing headphones or microphone is not working, you should first check the system sound panel. You can open it up through the control panel or the sound icon in the system tray. Some applications can automatically mute system sound, which may be the reason you can’t hear anything using your headphones. If anything is muted in the sound panel, try unmuting it.
In order to troubleshoot your headphone, you should play a sound file on your computer as you try different things so you can hear if the headphone starts working again.
Most people have speakers to go with desktop computers (and built-in speakers with laptops). If you do, you can easily check if your headphone works or not by unplugging it and connecting the speakers to your computer. Now if you can hear a sound file play, your headphones may be faulty.
You can also open sound settings from the control panel to see if the output (headphones) and input (microphone) is properly connected and recognized by the computer. Sometimes the drivers for your sound card may need to be installed. These are often found on the system disk which accompanied your computer or on the manufacturer’s website.
If you are not sure whether your headphones are faulty or your sound card, you can always connect your headphones to another device (all high-end phones have a 3.5mm jack) to test them.