After upgrading to Windows 10 version 1803, a number of users have faced a strange issue that the microphone doesn't work in certain apps like Skype, Discord etc. The issue affects all types of devices inlcuding laptops, tablets, and desktop PCs. Here is a quick fix.
Microphone privacy settings is part of the Settings application which allows you to customize the privacy of your microphone. Recent Windows 10 builds can be configured to allow or deny access to Microphone for various apps installed on your computer and the operating system itself. Only if allowed, the OS and installed apps will be able to use your device's microphone.