iPhone just won't charge, no solutions work, HELP!

So my cousin's iPhone got a blocked sim as she didn't pay her contract, but she no longer needed the iPhone 4 she had because she upgraded to an iPhone 5 with a different contracter so she gave it to me. I've had the iPhone now for a good few months and basically use it as an iPod as it can't make calls or texts.

Everything has been great so far up until yesterday, I regualry charge the iPhone from a USB port on my television. I leave it in the port all night but set a two hour sleep timer on my television which powers off my television fully after two hours and by the end of the two hours the iPhone stops charging as there is no power going into the television however it was always fully charged after those two hours. Then two nights ago I did what I usually do and charged it via my TV in the morning it was only 77% charged which I thought was strange because it normally gets 100%. Anyway I used it like I normally did and late at night before I went to sleep the next day I had a skype call with one of my best friends via the iPhone which I regularly do, the iPhone was only on about 7% and the battery was falling rapidly so I moved a seat next to my TV and charged it as I skyped my friend which I also regularly do. However despite it being plugged into the port and charging like it normally does the iPhone kept charging then not charging then charging then not charging, I thought this was strange and I assumed there was a problem with the cable so I got a new charger cable and the same thing happened it would only charge for a few seconds then stop, so I told my friend I'd be right back and turned my iPhone off with the lock button I then tried to turn it back on and I got the image of a battery with the red bar so I assumed there was no charge in it anymore so I plugged it into my TV yet again with another cable and it just would'nt charge, I left it plugged in all night and in the morning around 10 hours later there was still no charge in it.

My iPhone has been dead since last night and this annoys me. I thought maybe the USB port on my TV was not functionaling properly so I plugged the charger cable into my Xbox 360 and that didn't work. Now I'm on my PC with the charger cable plugged in to my USB port and my iPhone and it still won't charge! Also iTunes won't recognise that the iPhone is plugged in.

The images that pop up are a battery sign with a small red bar at the left of the battery and also the same image but with a charger cable and the little lightning bolt under it. I've tried everything that the internet has to offer when it comes to troubleshooting but nothings worked! I got iOS7 a few days ago and I don't know if that is the problem, perhaps iOS7 has a serious battery life bug? Or is my iPhone useless now? Maybe the charger connector port on my iPhone is damaged? Or all three of my charger cables are?

Any help would be much appreciated!