A computer that will not start is alarming, but many no-power situations have straightforward causes. Start with the simplest possibilities and work towards the more complex.

Laptops: Battery and Charger First

  • Plug in the charger and wait two minutes before pressing the power button. A completely flat battery will not start immediately.
  • Check that the charger's indicator light is on. If not, try a different wall socket and check the fuse in the plug (UK only).
  • Try holding the power button for 30 seconds with the charger connected and the battery removed (if removable). This drains residual charge from capacitors.

Desktops: Power Supply Checks

  • Check the power cable is seated firmly in both the wall socket and the back of the PC.
  • Check the power switch on the back of the desktop (if present) — it should be set to the I (on) position, not O (off).
  • Try a different wall socket and remove any extension lead to rule those out.
  • Check whether the LED on the motherboard (visible through the case vents or window) is lit. A lit LED means the power supply is receiving power even if the machine will not start.

No Lights, No Sound at All

If there is absolutely no response — no fans, no lights, no sounds — the issue is most likely the power supply (desktop), the charger or charging circuit (laptop), or a blown fuse in the plug. Replacing the plug fuse is a five-minute safe job. Everything else requires a technician or careful investigation.

Lights On, Fan Spins, But No Display

If the machine powers up but nothing appears on screen, the problem is different from a complete no-power situation. Check the monitor is on and set to the correct input. Try pressing Caps Lock — if the light responds, Windows has loaded but the display output has failed.

One Quick Reset Worth Trying

For desktops, unplug the power cable, press the power button five times (to drain capacitors), then plug back in and try again. For laptops with removable batteries, remove the battery, hold power for 20 seconds, reinsert, and try.

If your machine still will not start after these checks, describe exactly what you see and hear when you press the button and we can suggest what to do next.