I am trying to charge my Iphone 4s and suddenly i can not get it to charge, what might be the problem?Brian

Are you using a original USB cable? if not, than it could be the cable. If you are charging the iPhone with your computer, sometimes the USB port where you plugged in the cable stops working. plug it into a different USB port.

the charger is one possibility. Does it charge via the ubs port on the computer and not the wall or vise versa?