there are a few major programs to do this, but i use this: https://diskdigger.org/download
there is a free version, but I use the paid-for version because its hella cheap and makes exporting the recovered data alot more findable.
basically, mount disk, do 'deep scan' option, select all file types, wait.
when done, sort through files. sometimes you get 10s of thousands of old jpegs among other things to sort. good times.
I suggest also saving .thumb and .thumbcache files, which contain thumbs of images sometimes long deleted and written over.
uh. ill elaborate on this in a later post in this thread.