It's NTFS. It's USB2. I'm using Ubuntu 13.04. It works perfectly fine on Windows (which excludes cable and hardware problems). I have two Ubuntu computers and it's not detected on either. It's about 500 GB.
Edits:
Following the first link, I input sudo lsusb in a terminal; before and after connecting the HDD. The difference was Bus 001 Device 012: ID 14cd:6116 Super Top M6116 SATA Bridge. There it is! ("sata bridge" used to appear in a windows notification when I plugged in the HDD in!). ...This means that Ubuntu detects it but is it not mounting it?
I tried this:
sudo mount /dev/sdb1 /mnt
But gives this:
mount: special device /dev/sdb1 does not exist
I also tried:
sudo mount /dev/sdc1 /mnt
but it stays with no output forever. I left it in background for about 30 min.s.
sudo fdisk -l gives out this:
Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xa42d04a3
Device Boot Start End Blocks Id System
/dev/sda1 63 80324 40131 de Dell Utility
/dev/sda2 * 80325 102481919 51200797+ 7 HPFS/NTFS/exFAT
/dev/sda3 263874558 312580095 24352769 5 Extended
/dev/sda4 102481920 263872511 80695296 7 HPFS/NTFS/exFAT
/dev/sda5 263874560 310505471 23315456 83 Linux
/dev/sda6 310507520 312580095 1036288 82 Linux swap / Solaris
Partition table entries are not in disk order
Disk /dev/sdc: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x5822aaea
Device Boot Start End Blocks Id System
/dev/sdc1 2048 976769023 488383488 7 HPFS/NTFS/exFAT
The part below "Partition table entries are not in disk order" takes about 5 minutes to appear.
The outputs of ls /dev/ | grep sd before and after connecting the HDD:
before:
sda
sda1
sda2
sda3
sda4
sda5
sda6
,after:
sda
sda1
sda2
sda3
sda4
sda5
sda6
sdd
sdd1
The second output has the lines sdd and sdd1 different from the first one.
IT SHOWED THE FILES!!
The command sudo mount /dev/sdd1 /mnt worked after I typed in sudo fdisk -l!!! Thanks a million!! :) :)