sorry to hear this
if film, negative by scanner or ipad+dslr > youtube has film to reproduce it
if CD/DVD, god bless you if no exposed under the sun due to data lost forever
if HDD, data recovery software, ching above!
Sd card, which is owned by my sister. She borrowed the camera with sd card for my bro to take photos about 10 years ago. I think my sister must deleted and overwrite with newer photos.
Is it possible to get them back?