If you want to add the sound into the slides quickly and conveniently when the recording in PowerPoint is not working, using an audio recorder as the alternative would be a better choice. The reasons that cause PowerPoint not recording audio can be complicated. If you are sure everything is fine with your microphone but still unable to add voice over to your PowerPoint, move on to the next solution. You can adjust the sound volume here as well. Right-click on your microphone to select it as Default Device. If you see the words Not plugged in appear, unplug the microphone and plug it in again to make the warning disappear.
Next, click on the speaker icon to open the Sound window and check if it is enabled. If your microphone has the On/Off switch, make sure you turn it on before recording. You should insert your microphone into the 'Mic In' jack. Usually, sound cards have three input jacks.
Make sure you connect the microphone correctly. The first thing you should check is that your hardware device is working.
