I think at this point you should try mounting the drive using Ubuntu or Puppy linux. When you attach the drive you will see a USB icon appear on the Puppy Desktop. Clicking once on it should mount the drive and a File Manager will open.Puppy Tahrpup tahr-6.0.5_PAE.iso is a smaller download than Ubuntu.
You can create a bootable USB flash drive with Rufus or burn a disk. If you computer came installed with Windows 8 you would need to disable SecureBoot in order to boot Ubuntu or Puppy. You may need to enable Legacy boot also. Backup any data on the USB flash drive if you use Rufus as it will be formatted.
If you cannot mount the drive then you will need to scan the drive using recovery software.
Scan the drive with Minitools Data Recovery. Other software that people have had success with is DiskInternals Partition Recovery but it is expensive.
There is PhotoRec in the Testdisk folder that will do the same thing but any file recovered has a generic name and correct extension. You would need to open the file and rename it accordingly. Also it recovers files in Real Time so you would need to move the files to another drive as they are being recovered if your internal drive does not have enough space to recover the data from the 1TB drive. File recovery will be in the Testdisk folder.