|Read the info at the link I provided. |
If there is nothing wrong with your AC adapter, the AC adapter's connection and the jack's connection in the laptop.....
The led you probably have that indicates the battery is being charged on the laptop when the AC adapter is connected to the laptop should light up even when the laptop is off, at least briefly when you first plug in the AC adapter, if not all the time.
If it does light up, the battery may get HOT after a half hour or so, if the led stays on continuously .
If it doesn't light up, you have some other problem, including possibly sometimes the main battery may develop an open circuit internally.
If you're not sure whether you have an led for that, see your Owner's or User's manual for the model.
By the way, if you have dropped the laptop, or have spilled liquid on it, since it last worked properly, those reasons are the most frequent reasons a laptop gets damaged such that it can no longer work properly.