All of my Calendar events are not showing in my calendar

From BlackBerryFAQ

If you are encountering an issue of all your calendar events now appearing in your calendar or your "today" theme screen, following the fix recommended below. This issue often occurs after upgrading from OS 4.1 or OS 4.2 to a OS 4.5 wherein your calendar events are tied to email addresses on your BlackBerry.

• Do a complete backup of your BB as a precaution before proceeding.

• Do a complete sync to Outlook of your calendar events.

1. Delete your email accounts from the appropriate BIS website.

2. Hook up your BlackBerry to the Desk Top Manager using a USB Cable.

3. Open the “Back up and Restore” then go to advanced.

4. Then go to the box on the right hand side “device database”, Clear the calendar entries.

5. Disconnect the BlackBerry from the Desk Top Manager.

6. Remove the battery with the BB powered on; leave it off for a minute or two.

7. Put the battery back in and allow the BB to reboot.

8. Re-enter the email account(s) into the appropriate BIS website.

9. If you have more then one email account on your device, go into Options, then Advanced Options, then Default Services and choose which Email Account you want to be your default.

10. Re-sync your BlackBerry to Outlook.

• Note: An additional step during Step 1 above, might include deleting all your Service Books: Delete all the [CICAL] service books (there will be one per email account).

Thanks to zerog46 and JSanders @ BlackBerryForums.com for information in this FAQ.