There's a way for it. You'd need a computer and a software called "Recuva" (google it). Connect your phone to your pc (enable file transfer mode if needed), then open Recuva, follow the simple wizard and type your DCIM (photo directory) path into the window of it when asked to specify a path if known. Then enable deep scan to have higher chances to restore the files (it may take hours).
If you're lucky, you'll be able to restore all your photos or a good percentage of them, but beware if you did multiple data format, chances decrease drastically.
Good luck!