So what you have is a gaming headset.
Ie: Headphones with a mic on the headset on a arm where you can move it up or down to position the mic next to your mouth.
It is not selected as a Mic or a set of headphones.
Nor will any selection in the realtek bit of software provide it.
Instead first of all on the windows desktop right click on the speaker icon next to the time.
Select playback devices.
You will see if your headphones are connected a listing in playback devices.
Right click on it and select set as default communications device.
If you look up to the top of the window you will see the tab recording, click on it.
You will see a listing either of the headset or the mic of the headset.
Once again right click and set, or select...