Typically power supplies are the underlying cause of many of the problems that people face when using a laptop. Most laptop power supplies are proprietary, making the replacement of the unit expensive if one is needed quickly. While universal power supplies are available, it is advisable to only use a manufacturer's replacement power supply.
Using a laptop or even using the power supply to charge a laptop with a short circuit can be very dangerous. If you suspect that a short circuit may have occurred, have the laptop thoroughly checked out by a qualified service technician.
The heart of a laptop computer is the battery, which acts as the power source when the laptop is not plugged into an electrical outlet. A charging circuit takes power from the AC adapter and charges the battery. Should the battery become physically damaged, it can lead to various leakage problems which can be catastrophic to the laptop itself or the external power supply. It is always advisable to get the battery repaired or replaced if a visible inspection of the battery shows any sign of leakage.
A failing inverter can create a situation where the power supply is put into a state where it is asked to supply more power than it was designed to handle. While this situation is not typical, it helps to illustrate how the internal components that make up a laptop can create scenarios that will cause the external power supply to fail.
Liquid spilled on the laptop's keyboard can create any number of problems including a laptop power supply failure. While small amounts of spilled liquids might be tolerated larger amounts can cause a variety of power supply problems such as: a short circuit due to the liquid itself, a short circuit created by any dry residue remaining and a power supply failure directly due to corrosion. To establish the extent of a spill remove the various hardware components that can easily be accessed by the end user.