My n300 will not charge!

My n300 works perfectly but suddenly it has stopped charging. It only works when it is connected to the power cable. The battery meter says that it is charging but it doesn't. As far as I remember, it has never fallen nor has anything every spilled on it. It is new because even though I bought it in 2006 but I've barely used it 10 times. Can anyone please tell me what to do with it???