First, don't save anything to the hard drive with the photo data as it might overwrite the data. You can try some free data recovery software to see if you can recover files. It might be that the file table is corrupted with the actual data being ok. If you have two hard drives or partitions then save the recovery software on the one that does not have your data. https://www.easeus.com/data-recovery/data-recovery-software/free-hard-drive-data-recovery-software.htm