How do I fix a laptop that won't charge?

Isolating whether it is the charger, the port, the battery or the software, in that order.

Difficulty: beginner
Time: 20 min
Read: 2 min
Safety: caution

Short answer

Check the port for lint first — a wooden toothpick, gently, with the laptop off. Compacted debris in the charging port is the most common cause and the easiest to miss.

Four things sit between the wall and the battery: the socket, the charger, the port and the battery itself. Testing them in that order gets you to the answer without guessing or buying anything.

Safety

A swollen battery — a bulging case, a trackpad that no longer sits flat, a lid that will not close — is a fire risk. Stop charging it, stop using it and take it for repair. Do not puncture or press it.

Step by step

Try a different socket and remove any extension lead.Thirty seconds, and it rules out the cheapest possible cause.
Inspect the charging port.Look into it with a torch. Pocket lint compacts at the bottom and stops the connector seating. Clean it gently with a wooden toothpick, laptop off.
Examine the cable along its whole length.Particularly at both ends, where cables flex. Kinks, exposed wire or a spot that only works when held at an angle.
Check the charger's own light and warmth.Most have an indicator. A charger that is completely cold and dark under load has usually failed.
Confirm you are using the right charger.Underpowered chargers — a phone charger on a laptop, or a low-wattage USB-C adapter — may run the laptop without charging it.
Do a power drain.Unplug, remove the battery if possible, hold the power button 30 seconds, reconnect. It resets the charging circuit and often restores it.
Check the battery health in the operating system.Both major systems report it. A battery flagged as failing or at very low capacity needs replacing rather than diagnosing further.
Update or reinstall the battery driver.On Windows, removing the Microsoft ACPI battery driver in Device Manager and restarting reinstalls it automatically. It fixes a surprising number of cases.

Tips

Buy replacement chargers from the manufacturer or a reputable brand. Cheap unbranded power supplies are a genuine fire risk and often underpowered.
Many laptops have a charge limit setting — capping at 80% to preserve the battery. Check that before concluding it is broken.
Unplug by the plug, not the cable. Most charger failures are at the strain point where the cable meets the connector.

If it doesn't work

Charges only at a certain cable angle

Cause: Worn cable or loose port — Fix: Replace the cable first — far cheaper. If it persists, the port needs resoldering.

"Plugged in, not charging"

Cause: Driver issue, battery health limit, or an underpowered charger — Fix: Reinstall the battery driver, check for a manufacturer charge limit setting, and confirm the charger wattage.

Runs on mains but battery stays at 0%

Cause: Battery has failed — Fix: Replace the battery. The laptop is otherwise fine and this is usually an inexpensive repair.

Nothing at all with any charger

Cause: Port or internal power fault — Fix: Needs a repair shop. Try a known-good charger first to be certain.

Questions people ask

Why does it say plugged in but not charging?

Commonly a driver problem, a deliberate charge limit set by the manufacturer, or a charger that does not supply enough power. Check all three before assuming the battery.

Can I use any USB-C charger?

It will often run the laptop but may not charge it if the wattage is too low. Match or exceed the original charger's rating.