How to Test Your Laptop’s Battery
Laptop batteries can fail, or over time can lose their ability to hold a charge. If your laptop suddenly stops cooperating, you can usually determine if a bad battery is causing the problem by removing it from its bay (on the bottom or side of the laptop) and running the laptop from the AC adapter only. If the batteryless laptop runs properly when connected to the adapter, the battery has most likely kicked the bucket, shuffled off its mortal coil, and otherwise become defunct.
You can further test this hypothesis by substituting a battery that you know is functioning well from another laptop of the same model. You may be able to borrow a coworker’s battery or take the laptop to a cooperative retailer’s repair counter.
If, in the other hand, your batteryless laptop doesn’t run when connected to the AC adapter, either the adapter or the laptop’s internal electronics have failed. Again, if you can borrow a known-good adapter, use it to see if the problem is caused by the cords or converter or if the issue lies deeper within the laptop itself.