Why does my laptop not charge when plugged in?

The charging path has several links, and testing them in order is faster than replacing parts speculatively.

Start at the wall. Try a different outlet, and check the adapter indicator light if it has one. Power supplies fail more often than batteries do, and the failure is frequently in the cable rather than the brick, particularly at the strain points where it enters either end. Bending the cable gently while watching for intermittent connection is a crude but effective test.

Check the connector at the laptop. Charging ports collect debris, and the pins can be damaged by repeated insertion or by a cable pulled sideways. A connector that only charges at a particular angle is a physical fault rather than a software one.

For machines charging over a universal port, the specification matters. Not every such port supports power delivery, and not every charger provides enough for a laptop. A charger designed for a phone will often connect and negotiate a low power level, resulting in extremely slow charging or none while the machine is in use, which looks like a fault.

If power reaches the machine but the battery does not charge, the battery may be reported as failed. Most systems expose battery health, and beyond a certain degradation the firmware will refuse to charge rather than risk it.

One software case is genuinely common and easy to miss. Many manufacturers ship charge limiting features that stop at a percentage below full to prolong battery life. A machine sitting at eighty percent and refusing to go higher is usually working as configured rather than failing, and the setting lives in the manufacturer utility rather than the operating system.