Hi,
That is one way to prevent this if the little ones are kids.
However if little ones are cats for instance that just happen on the keyboard when you are legitimately in your Own account then nothing can really be done.
The main issue is to devise a search method that might turn up a pic or two (as a Starter if you like)
1) what was used to rename them
iPhoto has an Originals Folder
Go to ~/Library/Pictures and Right click the iPhoto Library.
2) If it was done in the Finder are the change name items in the same folder they were in Originally ?
3) other apps and Save As or the save function may not be pointing to the same place the items were placed in if a significant amount of time has passed.
4) If these files/pictures were ever subject to a Time Machine Back up and you kow where they should be then you may be able to find them that way.
5) My current Mac User Account on my iMac has a previous Mountain Lion Clone that would take me back to the Mavericks release.
5a) Prior to installing Mountain Lion I had Lion and the Accounts was actually Migrated from my G4 computer
Some things such as iPhoto are "Split" from this time. As is iTunes to some extent with newer purchases.
The G4 is running Leopard and can boot back to even earlier (file wise) to Tiger (OS X 10.3.9)
6) If the time delay is not that old then each apps Recent Items may also help.
I have mine set to 20 items (System Preferences > General setting - this will not increase the current list - it grows over time/use)

10:02 pm Wednesday; November 27, 2013
iMac 2.5Ghz 5i 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad