I solved the problem myself.  What I had to do was go into Library/Preferences/Audio, and delete the preferences.  Then I emptied the trash and restarted the machine.  New preferences files were created and the problem was solved.

What surprised me though is that this used to be the classic fix for the old OS 9 and earlier pre-unix operating systems. I did not know you could do this with OS X too.   It would also seem that no else knows it too, because of the hundreds of sites and forums I have read in the last 4 days.  This solution was never once suggested by any.

Hello and welcome to Apple Support Communities, Guitardoug.

If I understand your post correctly, your iPhone sometimes makes no sound or vibration when you receive calls or other notifications. I understand how important it is to be alerted to all your messages. I'd like to help.

Try the troubleshooting steps in this article:

If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker

For more details about Do Not Disturb, check out this article:

Use Do Not Disturb on your iPhone, iPad, and iPod touch

Let us know if that resolves this issue for you. 

Thanks for using the Apple Support Communities. Take care.

Three things to check:

1. The MUTE switch on the left side of the phone above the volume buttons
2. The volume settings when viewing the Home screen (either the buttons on the side or the Control Center)
3. Do Not Disturb settings - there will be a crescent moon in the status bar at the top of DND is enabled - change them in the Settings app

MY IPHONE X IOS 11.2.3 NO SOUND NO SPEAKER AFTER restart DEVICE ITS OK AND IOS 11.2.2  AGAIN this problem and again every two or three days totally pleased please help me

Hi

Apple Watch supports using compatible Bluetooth headphones that are paired to the watch for listening to music from your Apple Watch, but not for making or receiving phone calls.

If you would like to submit a feature request to Apple, then you can do so here:

• Feedback - Apple Watch - Apple

I have found the solution myself:

https://www.reddit.com/r/iPhoneX/comments/7tttkh/ive_found_what_caused_usb_dac_i ssues_on_iphone_x/?st=jd0h8wzz&sh=a087f4…

You haven’t even tried

Tried everything I could read. Finally remembered a trick I picked up during a conversation with Apple Store in my town: restart in recovery mode with this key combination: Cmnd-R-P: hold these keys till apple logo appears. Then a utility window will open, you do not have to take action there, just quit utility and restart.
Little things like sounds will (should) be repaired. In my case it worked.
For now
Hope this helps those who are still looking for a way.

You definitely need to uninstall MacKeeper and CleanMyMac3. Not sure if it caused your audio problem but they were both installed the day you started having the problem.

You also don't need two ad blockers in Safari.

1. Reset NVRAM/PRAM couple of times.  http://support.apple.com/kb/PH18761

2. Reset SMC. Choose the method for “If the battery is non-removable”.

    https://support.apple.com/en-us/HT201295