My iPhone 4 sleep/wake button is broken?

My phone isn't that old, I haven't had it for a complete year yet but I've dropped it a few times only on my bedroom floor which is wood. It's never cracked or anything. In the past week, I've noticed that I haven't been able to here it make the 'clicking' sound when I hit the sleep/wake button. Not the sound effect but when I hit the button down and it clicks. It's stuck now and I can't shut my phone off at all. Where can I take it to fix the button that won't cost a whole lot? What may have caused this?

I think there isn't a way you can fix that you have to take it to the place you got it from or like walmart or a repair store i have had the same problem it only costs $75-$100 good luck i hope you find someone who fixes it