We get a lot of questions that go something like this ‘My appointments prior to [a date] disappeared from my calendar; only recurring events remain. How do I retrieve the appointments?’

This happens either because AutoArchive is enabled or because you are syncing with a mobile device and the device is set to keep a limited number of appointments. When they are deleted from the device, they are deleted from Outlook on the next sync.

If they were removed by AutoArchive, they should be in the Archive PST. If syncing removed them, check in your Deleted items folder. If they are not in the folder and you don’t have a backup, they are lost forever.

Check Tools, Options, Other, Autoarchive to see if sync is enabled or right click on the Calendar folder and choose Properties, Autoarchive tab to change the settings on the folder.

If you use a handheld device, check the settings in the sync software or on the device. (On a Blackberry, open the calendar, press the button to expand the menu and choose Options. The setting that controls how long items are kept is near the bottom of the General Options.)