Try booting the hdd through linux , something like ubuntu. Its a freeware and u can TRY it and no need to install it. The files will show up when the hdd is accessed through linux. Cut the folder/files , create a new folder , paste the files/folder restart to windows and then try accessing the hard disk drive. The HIDDEN files shud be shown in the folder u pasted. I have recovered 2 HDDs in this method. While restarting if there is a disk check that runs please don't skip it. Linux is one of the best ways to recover the most bad ass hdd