So, if you’ve already tried the basic sound settings and you can HEAR sound in your headset but not SPEAK, then try the following so you can get back up and rolling:
1) In the bottom left-hand corner of the screen you will see a search bar that says “type here to search”. You will want to type in “Microphone privacy settings”
2) Ensure that “allow apps to access microphone” is turned ON
3) Under Choose Which Apps Can Access Your Microphone make sure all of the applicable apps are slid to ON
Note: Softphone applications will often not appear in this list. In those cases, simply moving the "Allow apps to access your microphone" slider to "ON"