Windows 10/117 min readReviewed 2026-07-29

Windows thinks Alt is held after the keyboard is unplugged

Find another HID device or input utility sending a stuck Alt-down event.

Quick diagnosis

If Alt remains held after the main keyboard is physically disconnected, that keyboard cannot be the current event source.

1
Prove the main keyboard is not sending it
Unplug the keyboard and observe the On-Screen Keyboard Alt state.
2
Disconnect other HIDs
Remove macro pads, controllers, docks, charging pads, and pass-through accessories one at a time.
3
Exit input utilities
Close remote-control, macro, and remapping programs individually.
4
Reconnect one at a time
Identify the exact device or process that makes Alt return.

Update, reconfigure, or disconnect the confirmed source rather than replacing the main keyboard.

• If no physical device explains it, use a clean boot to isolate injected input software.

Yes. Many accessories expose a keyboard-class HID interface for shortcuts or macros.

Alt key always pressed even without keyboard
Reddit TechSupport. A USB accessory reproduced the stuck modifier symptom.
Mouse and keyboard problems in Windows
Microsoft Support. Direct-port, battery, cable, hub-bypass, driver, and cross-PC diagnostic order.

Diagnose it in this order

Unplug the keyboard and observe the On-Screen Keyboard Alt state.

Remove macro pads, controllers, docks, charging pads, and pass-through accessories one at a time.

Close remote-control, macro, and remapping programs individually.

Identify the exact device or process that makes Alt return.