Can't find old HDD

[Monkeyman]

That is a removable device?
undo what you did to /etc/fstab
try to mount it this way

Code:

mount -t ntfs-3g /dev/sdf /media/external

Code:

mount -t ntfs-3g /dev/sdf1 /media/external

It's a HDD in a USB external enclosure.  I undid whatn I did to /etc/fstab (removed that last line) then tried both new commands.  I got "only root can do that" so I added "sudo" to the front end.  Here's what I got.

monkeyman@monkeyman:~$ sudo mount -t ntfs-3g /dev/sdf /media/external
NTFS signature is missing.
Failed to mount '/dev/sdf': Invalid argument
The device '/dev/sdf' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

monkeyman@monkeyman:~$ sudo mount -t ntfs-3g /dev/sdf1 /media/external
ntfs_mst_post_read_fixup_warn: magic: 0x44414142  size: 1024  usa_ofs: 20480  usa_count: 36364: Invalid argument
Record 0 has no FILE magic (0x44414142)
Failed to load $MFT: Input/output error
Failed to mount '/dev/sdf1': Input/output error
NTFS is either inconsistent, or there is a hardware fault, or it's a
SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows
then reboot into Windows twice. The usage of the /f parameter is very
important! If the device is a SoftRAID/FakeRAID then first activate
it and mount a different device under the /dev/mapper/ directory, (e.g.
/dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation
for more details.

Since I don't know what that means, I'll leave things alone until I hear back from someone.  I'm not running Windows so I don't know what that has to do with anything and it's never been RAID'ed.