This feature has been updated to include a preview that this video doesn't show. All other functionality is the same, view updated details below.
How to Restore a Slide or Chapter
Select the Presentation drop down and Select Restore Deleted Slides
You'll be presented with a list of deleted slides and chapters. Preview slides individually or restore multiple slides and chapters at once.
If a slide's chapter is also deleted that must be restored as well
You can also view who deleted and when a slide was delete use the info icon to view these details.