My iphone 4 not charging all of a sudden?

Okay, so I have an iphone 4.It's been absolutely fine for the past year or so that I've had it. But yesterday, I hooked it up into the wall charger, and it didn't vibrate the way it usually does (indicating that it's hooked up to an electrical source and thus charging). I turned it off and then turned it back on again, and it then said that it was charging. I've had to do this several times since yesterday.

But now, it's not charging at all. Not in the wall, and not on the computer. My computer's not even saying that a device is hooked up into it.

I'm frightened because I have less than half a battery left, and I really need to know what the heck is wrong with my phone. Is it the cord? Is there something wrong inside the phone? Have I dropped it one too many times and it's just jacked up now?

Well, it may be your charger, BUT this exact thing happened to my ipod 5. My older brother gave me a wall plug in, so i could charge it in the wall, also he gave me a car jak so i can charge my phone/ipod in the car as well.
http://www.ohcases.com/wall-home-and-car-charger-lightning-to-usb-cable-for-iphone-5-5s-5c-ipod-touch-5-ipad-mini/ just copy and paste, this price is a pretty good deal.