Why my laptop is not able to charge?

There could be a couple of problems to check. First your charger might be broken, or the part that plugs into the computer could be broken or bent. The part in the computer that connects the charger could be broken or dirty. And the battery could be dead or close to it which you would need to replace it. The cable connecting the batter to the laptop could be loose. Also after the computer is fully charged it should be unplugged because you could be over charging the battery.