Just let me jump in here.
The internal photos are in a folder called DCIM the photos can be saved to external sources via hooking via USB and then going to said folder and doing a copy paste to a new folder you can create on your computer or on an microsd or sd card.
Under gallery there is an option to have photos by default save to the sd card. this way you will always have them.
The suggestion of getting hold of the buyer of your old device to assist you in getting them back is a good idea.
But if the phone has been wiped they are now gone. Lo sentimos.