I was having issues with my phone and was told to do a factory reset by Samsung customer support but I didn't backup my phone cuz I have it set to backup already and never had an issue recovering photos until now! I had no idea that the gallery had to be backed up through Microsoft onedrive and now I have lost 12 years of pictures and videos! Please someone tell me there is a way recover these pictures, if not I'm going to be crushed! Thanks!
Unless you were saving them up to a cloud service like Google photos or one drive. Or backed them up to your computer....I can't think of a way to retrieve them.