A laptop power supply, or PSU, is what gives the laptop its power to function. It is also used for charging the battery of the laptop. If it is not functioning already, you will not be able to charge your laptop. A replacement can easily be installed if you know what type of power supply you have.
Double-check if the power supply of your laptop is not working by plugging it to an outlet and plugging the other end to the laptop. You can turn on the laptop or you can just check if the battery light on the side of the laptop lights up. If you want to turn on the laptop, you will see the status of the battery on the lower-right portion of the desktop. It will indicate a charging status if your power supply is functioning normally.
Check the connections of the power supply and the cords. Sometimes loose plugs will prevent the power supply from providing the needed energy to the laptop.
Try to move the cords of the charger that connects the power supply to the laptop. Sometimes the power supply is not really the part that is damaged, but it could be the cord. If you move it and it charges, that means the cord is damaged.
Bring the power supply to the store if the troubleshooting confirms it is not working. Bringing the power supply to the store will ensure you that you purchase the right model. You can also bring your laptop to test the new power supply. It will also save you the unnecessary trip back to the store, if the new power supply does not work.
Throw the old power supply in the proper trash can. It can be hazardous if it is mixed with the regular trash.