You should try a drive recovery freeware that has helped me recover many of my files from a "not formatted" drive and format this drive to return its normal use afterwards. Note:
1. Do not store any new data on this drive to avoid the original data overwritten by new data, which can make it gone forever.
2. Do not save the recovered data on the same drive in case of recovery failure.
3. Do not forget to format this drive after recovery failure.
4. Do not forget to back up your important data regularly on a different drive in the future.