chance of successful repairing jpg is very difficult.. If you can get the RAW from source then just go on from there and reconstruct..

JPG is compressed information and it use compression algorithm.. To rebuilt you need to know a fair bit more information than just pray.. In short.. you need a lot of homework done.. Unlike old days Bitmap that is easy..

Best of luck.. good to keep at least one copy backup and store offsite. to be recycle on a regular basis to verify.. else use cloud but that need annual maintenance cost..