If you find that you can’t Play YouTube Videos on a Windows PC after doing so the previous day, I may have a simple fix for you.
The first troubleshooting tip is to trying to do a sound test from the Windows Taskbar. While doing the sound test, if you receive a message informing you that your device is already using the audio, please save all your open documents and restart the computer. When you attempt to replay the video again on YouTube, it should work now. If not, you have also confirmed that your sound drivers needs to be reinstalled.
If the video playback is green and sound can be heard, follow the tips based on the browser being used at the time.
Keep in mind that to interact with YouTube.com, you will need one of the supported browsers for YouTube to avoid error messages. If you have it, update it or download a competitive version.