This is my first post in this forum. I have already used TestDisk and GNU ddrescue to successfully rescue two hard drives that were dying from my NASlite-M2 x64 system. One of the Hard Drives was a 120 GB EIDE HD that lasted for 12 years!
I am having an issue with a 2TB Seagate HD that appears under Terminal (I am using Elementary Freya Linux, a variant on Ubuntu) but is unable to mount, or properly allow a run through of TestDisk and allow me to view files.
Background info - The 2TB HD was in NASlite-M2 server which formats the HD's using the ext2 format. It was working perfectly and had 1.9TB of data on it, and then one day it stopped mounting

In Elementary this device ('/dev') is /dev/sdc. I ran TestDisk and had the following errors (see attached screen shots):

I then got an error about partition sector not having an "endmark of 0xAA55" (see image below):

Using the "fdisk -l" command in terminal, I get the following breakdown, and again it is /dev/sdc (see image):

I have been scratching my head trying to figure out what happened, and what to do next. I patiently look forward to any and all help that I receive, and will do my best to report back all of my experiences with a resolution.