Well, the standard answer is, they are gone. Which is very true. This is why I am always telling people to back up their photos, videos, and other personal info to a cloud account or computer. For times just like this.
That said, there 'may' be a way for you to get them back, 'maybe'. There is no guarantee it would work.
There are actually a few apps/programs out there that "may" be able to help you recover the data.
A few of the programs you could try would be... DiskDigger, MobiSaver, Android-Recovery and Tenorshare. They are all data recovery apps/programs. There are many others out there, so check around and see which you would rather try.
One important note though, most of these programs are not free. They may say they are "free" or have "Free Trials" and "Free Downloads". Yet to actually recover your data, and get your files back, you may be have to purchase the program/app. Just so you know.
For future reference, I really would suggest backing up your data to a computer or cloud. Often. Better to spend the time doing that, rather than to be out all that stuff if the phone dies, things get deleted/erased or it gets stolen.