My iPhone 4/4s won't charge...

Well, this one can be a little nasty... First, inside the charing port you will see a tiny little rectangle to the side of the charging port facing the back of the phone. If that water damage indicator is red, you have a damaged port and you will need to have it replaced. However, if you cannot see it, it looks gray or black and the charging cable does not go all the way flush as it did before...it is filthy in there! Make sure the phone is off, and use a very thin toothpick to pick out the lint and dirt then use compressed air to get that stuff out. Keep working at it until the charing cable connects flush to the phone and you should be good to go.

-Happy hunting.