Q: World Clock is gone on Notification/Today Window?

Hello !

           please click on edit ,

Click on plus sign in world clock

It will be moved in today's section

Finally , click on done .

Thanks !

So , you tried the method it's still not showing .

Please go to go folder :

Open preferences folder you will find a plist

Right click on it and move to trash .

In the same way in system library

Please click on go to go folder /Library find preferences and right click on the plist and move to desktop ( don't delete it ) .

Then , restart the computer & empty the trash . Once again drag and drop the com.apple.timezone.auto.plist to it's original place .

Thanks !

You have to enter in system library .

I have found an article , hope so it might help you : OS X: Correcting the time shown in the World Clock widget - Apple Support

Thanks !