If you have rejected an event and wish to restore it, follow this step by step process.
Step one: Find your Rejected events at the bottom of the list of sources/categories. You can also search for the event by name in the Search by keyword(s) box.
Step two: Click on Manage for the event you wish to restore. Although the box is grayed out, it is still clickable.
The event will immediately be restored to your calendar.