Q: syncing calendars...

The first thing to do is to figure out which of your two devices isn't syncing, your computer or your phone.  To do this, go to icloud.com from your computer and open the calendar.  Then add a new event on both your phone and your computer to see which one fails to appear on the calendar on icloud.com.

When you do this, which one is not syncing new calendar events to icloud.com?

When I do this neither the New EVent on the iPhone Calendar nor the NEw Event on teh Mac show up.  ALso in the iCloud calendar none of my old events show up.

Is you computer a PC or a Mac?  What version of Windows or OS X are you using?

Also, are you signed into iCloud in Settings>iCloud on your phone with Calendars set to On?

My computer is a mac with newly installed Mt. Lion ( 10.8.4)  I am signed into iCloud and the Calendar setting there is set to on.  This lack of sync ablility started after I upgraded to Mount Lion from Snow Leopard.  Thanks veyr much for responding.

Just to confirm, did you say when you check your calendar on icloud.com, that your calendar is empty?

yes

Open Calendar on your Mac so you can view your calendars on the left sidebar.  If you can't see them, click Calendars on the top left.  Are each of your calendars listed under "iCloud" or something else like On My Mac?

I have a screen show that is a little awkward to view but it shows you the calendar.  I have lots more items taht the one item that shows up

the msg you jsut got was sent before your most recent question.  I will answer you question now.  Stand by

THe calendars are listed under iCloud.  THey are also listed under other items as well.  I have all calendars checked off.

on my iphone my calendars are also listed under iCloud

I don't understand what you mean.  I'm asking you to launch the Calendar app on your Mac and see if your calendars are listed under "iCloud" (like the image below) or something else.

Check only the calendars listed under iCloud (and uncheck the others).  When you do this, do your events appear on your calendar or are they empty?

I checked only the calendars under iCloud.  All events disappeared.