I fire-up the computer out of sleep mode. So, it should be function as it was the previous day? Not today as there was no sound.

The troubleshooting begins:
- Oh no, maybe it's the headphones. Unplug the headphones which runs through the speaker system. No sound.
- Maybe, it's the volume settings in YouTube. Check the setting. Looks okay.
- Check the computer main volume. Nope. Is it muted? No.
- Maybe the speaker volume is turned down? No.

- Ah, maybe I kicked a wire and there is a disconnection with the speakers or the computer. No, again.

- Damn it. Did the audio card burn out? Pull the side panel off the computer. Perhaps the audio card is loose? Push-in the card to ensure a proper seating. Okay.
- No electrical burning smell as I sniff around the audio card.
- Update the audio card drives. Already using most up-to-date audio drivers.
- Still, the card is old. Maybe, it died? Change connections to integrated motherboard audio. No sound.

- Double check YouTube, main computer, and speaker volumes. All okay.

- Well, what about the motherboard. Go get the flashlight (torch). Appears to be okay.
- What the hell is going on?
- Go get something to drink.
- Hmmmm? What the hell?

- Use another audio source to see if it is YouTube. No sound.
- Check the audio settings on the new source of sound. Esta bien.
- What about the tried-and-true technique of techniques? Restart the computer.

Voila!!! Can you believe it? Restarting the computer did the trick.

Back to thoughts of concern as I have no clue as to what was wrong. Perhaps, something really serious is beginning to fail...