My iphone 4s wouldn't charge either and I thought it was going to need a new battery or something. My husband looked at it and said the cord was not making good connection with the port. He plugged it in and set something under the cord to elevate it so that it was laying just a little elevated. Immediately the green light and the charging symbol came on! Now my phone will charge very quickly as long as I put something under the cord to elevate it and ensure a good connection! For mine a wooden coaster I have works just right.