Recovering recent Microsoft Office files despite closing the default notification

If you were interrupted before you ever got the chance to save your PowerPoint file, you can simply look for it in the Microsoft Unsaved Files folder. Go to the File tab, make sure you're on Recent and click on Recover Unsaved Presentations. The icon is right below the list of folders under Recent Places.

source: https://slidestore.com/blog/recover-unsaved-powerpoint-file/