what if my photos just disappeared after a software update?

The first place to look would be your recently deleted folder. Open the Photos App. Tap Albums. Look for Recently Deleted. If they are there, they can be restored.

If that doesn't help, open the Settings App and Tap your name at the top. Then tap iCloud. Make sure Photos is turned on.

As an avid Apple user, of course the first place you look are deleted pictures, but obviously you’re not gonna delete pictures that are near and dear to you and I was just discussing this the other day with someone that my pictures seem to just randomly disappear so we obviously are not the only ones asking this question!!!!