Where do your photos save to by default? Typically, being that the memory used for mobile devices it usually flash memory, depending on the phone, the data is not really deleted, but more or less "hidden" and gets written over when new data is added. On flash or solid state storage, they are saved in blocks, as opposed to HDD's that use platters (not sure how to describe it). So your chances of recovery are decent, if you can find a decent piece of recovery software. I'm not saying you won't have to pay for it, but that might be your last hope if you really NEED those pictures back.
Hopefully someone will have a better answer for you in regards to getting the images back. I know it is not impossible but I think you might have to spend money to do it if no one else has a way to do it.