Actually, if you reset the phone, and you hadn't had them saved either to a google account (and recently synced to it) or saved to an SD card (that was not in the phone when the reset was done), then those pictures are almost certainly gone. I mean you can try the following, but to be honest, I wouldn't bet much on it working for you. A reset is meant to wipe a phone of all your personal stuff.
There are 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. There is also one called...