1. If the laptop is over 3 years old, the battery is probably useless now or completely dead.
2. If the laptop is old enough take it in to repair shop and see if they have batteries that are compatible and have them test and then you can buy the battery and call it a day.
3. If the battery is good and laptop just out of warranty then remove battery and charger and hold power button down for 30 seconds and then reattach battery and charger and test. In some rare cases a laptop may have non-soldered cmos battery, and if easily accessible by removing panels on the back that are designed to allow easy upgrade of ram and even cpu in certain cases will also reveal the cmos battery when the panels are removed. In this case remove the cmos and...