Can I retrieve pictures that my 3 year old deleted from my iPhone 4s?
I don't think you can. That's why I think it's a bad idea to let kids play with cell phones. ;o
If you made a cloud account your phone backups everyday , just restore from backup to get pictures back , if you didn't well your out of luck
If you have iCloud maybe...?
If you had the pics backed up on iCloud or your comp you can. Otherwise I don't think so.