I Think Some Activities are Missing from my Calendar?

If you find that all activities have disappeared from your calendar, it could be that the activity type has been de-selected from your view.  Don't worry!  To see if this is the case, go to the Calendar and look at the top header.  If any of the activities have a white box, that means it has been de-selected.  Simple re-select the box, and your activities will re-appear (they have not been deleted).