1. Identify what the screen is doing

Can the monitor display its own menu or a no-signal message? If even its menu is missing, check its power first. If the menu works, select the input you actually connected, such as HDMI or DisplayPort.

Note what changed before the fault: a new cable, dock, update or wake from sleep. Use that information to choose the first useful test. Changing everything together makes it harder to know what restored the picture.

2. Simplify the connection

1. Reconnect the video cable at both ends.
2. If a dock or adapter is involved, try a compatible direct connection.
3. Try a known-working cable, then another available video output.
4. If possible, test the monitor with another device.

Each test should answer a question: does the cable work, can the screen display another source, or does the issue occur only through the dock? Success with another source narrows the search, but does not prove support for every resolution.

Do not buy an adapter just because the plugs look right. For USB-C, the PC documentation must confirm video output on that specific port.

3. Select the projection mode

Press Windows + P. Choose Duplicate for the same picture on both screens, or Extend for additional desktop space. Allow a moment for the change.

Open Settings → System → Display, expand the multiple-display options and use Detect. If both displays appear, identify them before arranging their positions.

An extended desktop can look empty simply because no window has been moved there. Drag a window onto the second display to check the result.

4. If it stopped working suddenly

Save your work. Windows + Ctrl + Shift + B resets the graphics driver and may cause a brief flicker. If that does not help, restart the PC normally.

If the fault began immediately after a graphics update, record its date and driver version. Microsoft’s troubleshooting instructions explain when rolling back a driver is appropriate. Prefer a targeted investigation to installing several unidentified driver utilities.

On an organisation-managed PC, give these observations to its support team rather than changing centrally managed drivers.

Check the fix

Check the desktop picture, moving a window and then opening the game. If only the game goes black, the desktop connection works; focus the next investigation on the game’s display mode and settings.

Record the working connection. Reconnect removed accessories one at a time. If a dock or additional monitor triggers the fault, check the hardware limits. A video splitter does not necessarily create independent extended displays.

Sources and scope

Prepared from official documentation checked on 20 October 2026. Windows labels can change between versions. This guide does not claim hands-on testing on every PC.

• Microsoft — dépanner les moniteurs externes (French source)
• Microsoft — utiliser plusieurs moniteurs (French source)