I have an article here for you that can help you troubleshoot this issue with your iCloud calendar syncing:
If you're having trouble with iCloud Calendar on a PC (with Outlook 2007 or later), try each of these steps, testing after each to see if the issue is resolved.
Note: iCloud Control Panel does not support Outlook 2010 Personal Edition. When using iCloud Control Panel 2.0 and later, iCloud Calendar event descriptions in Outlook 2010 do not support text formatting (bold, italics, or underline), HTML, images, or attachments. The contextual menu (right-click) has also been disabled.
- Verify that you are using a Windows configuration supported by iCloud.
- Make sure that your computer is online. Attempt to view www.apple.com. If you can't connect to the Internet, your iCloud calendars and events will not update in Outlook. Learn about troubleshooting your Internet connection.
- Open a secure website to test if ports 80 and 443 are accessible. Outlook requires port 443 access to iCloud to push and fetch updates to and from the iCloud Calendar servers.
- Verify that your iCloud member name is entered into the iCloud Control Panel window. Learn about setting up iCloud on Windows.
- Close and reopen the iCloud Control Panel.
- Make sure that iCloud is not your default account in Outlook:
- In Outlook 2013 and 2010, select File > Info > Account Settings > Data Files. If iCloud is listed as the default account in the Comments column, select a different account and click Set as Default.
- In Outlook 2007, select File > Data File Management > Data Files. If iCloud is listed as the default account in the Comments column, select a different account and click Set as Default.
- If you recently made changes in Outlook and they are not updating on your other devices or vice versa, click the Refresh button in Outlook.
- Turn iCloud Calendar off and back on:
- Close Outlook.
- Open the Windows Control Panel:
- In Windows 8, go to the Start screen, then click the iCloud tile.
- In Windows 7, choose Start menu > All Programs > iCloud > iCloud.
- Deselect the checkbox next to Mail, Contacts, Calendars & Tasks, and click Apply. Wait a few seconds, then replace the checkmark and click Apply.
- Open Outlook and test to see if the issue has been resolved.
- Make sure that the iCloud Outlook Add-in is active within Outlook:
- Outlook 2013 and 2010:
- Open Outlook 2013 or 2010.
- Click the File menu.
- Click Options in the left panel of the Outlook window.
- Click Add-Ins in the left panel of the Outlook Options window.
- Look at the list of add-ins beneath "Active Application Add-Ins" and verify that "iCloud Outlook Add-in" is listed.
- Outlook 2007:
- Open Outlook 2007.
- From the Tools menu, choose Trust Center.
- Select Add-ins from the left column.
- Outlook 2013 and 2010:
- Learn more about managing Add-ins with Microsoft Outlook.
- Restart your computer. This may sound simple, but it reinitializes your network and application settings and can frequently resolve issues.
Note: When enabling Mail, Contacts, Calendars & Tasks in the iCloud Control Panel, part of the setup process is to copy your Calendars data from the default Outlook .pst file to iCloud, then remove the Calendars from the .pst file by placing them in the Deleted Items folder in Outlook. The Calendars data is then stored in the iCloud data set within Outlook so that changes can be pushed to and from Outlook by iCloud. Make sure that you're looking for your data within the iCloud folder in Outlook after enabling Calendars in the iCloud Control Panel. The deleted files can be seen by viewing Deleted Items within your Outlook Folder List. This is not iCloud removing your data. iCloud simply copies your data into the iCloud data set and then removes the local Calendars data by placing it in the Deleted Items folder.
Take care, and thanks for visiting the Apple Support Communities.
Thanks, Braden, but I didn't explain my problem fully. I have Office 2003 which is not supported by iCloud, but I'm not talking about an MS Office calendar. The calendar I use on my desktop is simply an iCloud calendar.
For a couple of months after installing iCloud on my Windows desktop and my iPhone4, I was able to view common calendar entries on both. They remained sync-ed and I was happy.
Now, however, there are no calendar entries on my iPhone. I don't know where they went. None of my desktop calendar entries show up on the iPhone.
The only things I remember doing between when it worked and now, when it doesn't, is that (1) I installed the new iPhone OS and (2) I used an AVG PC Tuneup software package to clean up and optimize performance of my desktop. The AVG people say I may find an answer by talking to Apple.
Hi again pipeleak,
How about this article, which deals with troubleshooting calendar syncing through iTunes instead of through iCloud:
There's also a link at the end of that article to some advanced troubleshooting steps if the issue was not resolved by the steps in this article. Hopefully that will get you on the right track toward resolving the issue. Thanks for coming to the Apple Support Communities!
Somewhere in what you sent me said that if you've upgraded your iOS, you need to re-initiate iCloud. I can't remember just how it was stated or where it was after all my rummaging around, but the upgrade on iOS that I had performed recently was the culprit. My calendar's back and I can go on with my life!