How to recover deleted photo album saved on internal memory - Note 3
Considering you phone is always writing some kind of data to your internal storage, it's going to be a very difficult to recover them - at least not all anyway. 

Unless something like PhotoRec can do it (as mentioned in the comments), I'd say they are gone for good. 

An alternative, and probably a very expensive one, is to take it to someone who specialises in data recovery. Search for 'mobile phone data recovery' on Google and see what appears in your area. It may mean sending your phone away.