NTFS drive wont mount - "unknown filesystem"?

[David McNally]

Hi Everyone.

Back when i used windows i got a 700 GB USB external hard drive. It
was formatted with NTFS because it was first set up on windows. I've
been using it since then on Ubuntu, without any problems. i never
bothered to reformat it as a better filesystem because the NTFS worked
well enough, and I didn't want to mess with it. However, it isn't
working properly anymore. Maybe someone here can help me.

I opened up GParted to see if i could find a problem with it. When i
go into GParted and select the hard drive, it tells me that the file
system is "unknown". Next to the word "unknown" is a black square. It
is able to determine the correct size (698.64 GiB), but can not tell
me how much is used and how much is unused. Under partition, it says
"/dev/sdf1" and then has a little orange triangle with an "!" in it.
When i go into Nautilus, the hard drive is not listed or mentioned in
any way.

I can tell that this isn't good, but I was hoping that someone had
maybe seen this before and might know how to help. It looks like the
rest of the computer is working just fine. Ubuntu boots from the
internal hard drive properly, so I'm still able to use the computer
like normal, but the external hard drive isn't working at all. I did
have quite a lot of important stuff on it, so it's pretty important
for me to be able to use it again.

Thanks in advance!

-- 
David McNally
david3333333 at gmail.com
Linux Kernel 2.6.31-17-generic