Nine Things That Often Go Wrong in PowerPoint 2013
You can't find your file.
Either you saved the file in a different folder, or you used a different filename to save it than you intended.
The most likely way to find your presentation is to check the list on the right side of the File menu. This list includes the presentations you’ve most recently worked on. If you don’t find the presentation in that list, summon the Open dialog box (choose File→Open→Computer) and then click one of the choices in Recent Folders. This displays a larger list of recently used files.
As a last resort, use the Windows search feature (on the Start menu) to find the presentation.