Computer will not turn on, or turns on with a black screen

First decide which of two problems you have: no power at all, or power but no picture. The checks are different.

What you seeNo lights and no sound, or lights and fans but nothing on the screen

A. No power at all: no lights, no fan, no sound

Laptop

1. Check the socket with another appliance, and the charger's connections at both ends. Look for a light on the charger or beside the charging port.
2. Do a power drain. Unplug the charger and everything else. If the battery comes out, remove it. Hold the power button down for 30 seconds. Reconnect only the charger (leave the battery out if removable) and press power once.
3. Leave it charging for 30 minutes and try again. A battery that is completely flat will not start the laptop at once.
4. Try another charger of the same rating if you can borrow one. Chargers fail more often than laptops. With USB-C charging, try the other USB-C port and a different cable.
5. Look for a small pinhole reset on the base of some laptops; the manual says how to use it.

Desktop

1. Check the wall socket, the power strip and the cable, and the rocker switch on the back of the power supply (I is on).
2. Unplug for a minute, plug in, try again.
3. If there is still nothing, the power supply or the front-panel button is the usual culprit. A technician can test with a spare supply.

B. Power, but a black screen

You see lights or hear the fan, but there is no picture.

1. Is it really starting? Listen for the Windows start sound, press Caps Lock and watch its light, or shine a torch at the screen at an angle: a faint image means the backlight has failed.
2. Brightness and display mode. Press the brightness-up key several times. Press Windows key + P, then the down arrow and Enter, up to four times, pausing between, to cycle the display mode in case it is set to an external screen.
3. Wake the graphics driver. Press Windows key + Ctrl + Shift + B. The screen blinks and may come back.
4. Desktop: check that the monitor is on and set to the right input, and that its cable is in the graphics card's socket, lower down on the back, not the motherboard's, if a card is fitted. Try another cable or the television as a screen.
5. Laptop: connect an external monitor or TV by HDMI. A picture there means the laptop's own screen or its cable is faulty.
6. Power drain, as in part A, clears many black-screen cases.
7. Remove what was added last: new memory, a new card, any USB device.
8. Reseat the memory on a desktop or a laptop with a memory cover (see MEMORY_MANAGEMENT for the safe way). Beeps or a blinking power light in a pattern are an error code; count them and look up the pattern in the maker's support pages.

C. Black screen with a cursor, after signing in

Windows has started but the desktop has not. Press Ctrl + Shift + Esc for Task Manager, choose Run new task, type explorer.exe and press Enter. If that works, see Start menu and taskbar not working. If Task Manager will not open, start in Safe Mode and remove the last update or graphics driver.

When to stop and get help

A burning smell, a clicking power supply, liquid damage, or a laptop that got very hot before failing: unplug it and take it to a service centre. Do not keep trying the button.

For Windows 11 and Windows 10. Written in November 2026. Menus move between updates; use the search box in Settings if a name differs. Back up important files before any step that resets, repairs a disk or opens the computer. This is an independent guide, not connected with Microsoft.