Open an Existing Powerpoint Presentation

If you want to work on an existing presentation, simply find the file on your PC and press Enter to open it in Powerpoint.
Or, open the Powerpoint application and, by default, it will take you to the Start Screen. Here you can Tab to a list of recently opened presentations. Arrow down the list and press Enter on the one you want.
If you do not use the Start Screen, press Control + O and here you can press Tab then Arrow down to different locations to find your existing presentation. Or Tab to the recently opened presentation list.