Hard drive suddenly not appearing on anything?!

Hello, I realise this is a commonly asked question, and I apologise for adding it to the large 'hard drive not showing up' collection, but after going through many different forums and threads seemingly covering the same problem, I still have gotten no results.

Moving on, my issue is a TB large Seagate (of course right?) hard drive that up until recently had worked perfectly (on many different pcs and tvs), however a few weeks ago, it started playing up and only working after a couple reinsertion attempts, and now it is at the point where it just isn't showing up on anything period (or on the computer at all).

Taking into consideration that it worked fine previously, and would previous work after cord fiddling, I strongly believe it may be an external problem. That being said, if it is at all possible that it is not an external problem, I'd like to try and manually fix it.

I am using Windows 7, and have attempted most methods of fixing this crap, but I'm desperate. Any idea?

Thanks guys.