Screenshots

@JMwonderland 
Ideally all screenshots taken in game go to Documents\Electronic Arts\The Sims 4\Screenshots unless directed otherwise.
To verify where they are saved go into game options and the "Screen Capture" tab. The "location path" is where the game sends the images.
If you are connected to any type of cloud save like iCloud or OneDrive for example your screenshots and/or game data could be going there.
Simply correct the path in the game options and that should solve any future problems.

To find missing screenshots you could try a search on your computer.
Screenshot names usually start with the date they are taken. Using that first part of the name you should be able to find your missing images.
Example:  08-28-19_12-44-46 AM

-EQ Avid Sims Player