My iPhone 4s won't turn on after stuck at 1

So my iphone randomly drained to 1% when i came back from school, and i could just charge it and it would be alright, even tough the battery displayed 1%, i could still use it throughout the day. I've had this problem for the third time now. The other times i got this problem i just let my iPhone drain untill it was dead, and then waited for a day or so, and then charged it again and it would turn on. But this time it won't work and i can't seem to get it on again and i really need my phone! Since the iphone displays a battery when it's off or drained, i've always tought that there's some battery percentage left to display the image of the battery. So i tried waiting 1 week to see if it dissapeared or not, but it wouldn't. Whenever i put the cellphone in the charger, it displays the battery as if it's charging, but no matter how long i let it charge, it wont turn on! Does anyone have a solution? Could someone explain why the iphone battery percentage sometimes goed randomly to 1%? did i do something for this to happen?