You need a software to do that. A program I know that can recover anything you delete is Recuva, google it. But you have to keep in mind that if you deleted something after the pictures there is a chance some of those might become unrecoverable. I can't really explain why it happens maybe someone with a greater knowledge about HDDs will be able to, it must have something to do with the sectors/blocks.
The first piece of software that you’ll want to try is called Recuva, and it’s extremely easy to use—just make sure when you are installing it, that you don’t accidentally install that stupid Yahoo! toolbar that nobody wants.Look here http/www.howtogeek.com/howto/15120/get-back-that-photo-picture-or-file-you-deleted-accidentally/