|You have three possibilities here, the battery will no longer take a charge, the power cord is not supplying enough 'juice', or the charging circuit in the laptop or other internal part (like charging jack) is bad.|
Try cleaning the battery contacts with a pencil eraser and then removing the dust and see if that helps.
Try seeing if the laptop will run on the power cord with the battery removed, if it will not, then the cord may not be supplying enough voltage or current to charge the battery. Unfortunately, if the voltage is only a little bit low, the laptop will run but the battery would only charge a little bit until the battery voltage reaches the input voltage (if this is the case, then suspect the cord).
Further testing may require that you could borrow a power cord and possibly a battery from another similar Samsung machine or bringing it in to a service center.
You have to be a little bit crazy to keep you from going insane.