Why is my battery not charging

Sounds like either you charger or DC jack is faulty. Ensure all leads are properly connected. Test your charger using a multimeter for the voltage given on the sticker on the charger. If you are getting the correct voltage, it maybe the DC jack which is a common fault on laptops. You can test the DC jack by opening the laptop up and testing for voltage where the jack meets the board. If the DC jack and charger are working, the power board is probably at fault.