Speakers Not Detected, Fix Missing Playback Devices
Speakers that Windows does not detect are usually disabled, disconnected in software, or hidden behind the wrong default output. The speakers themselves are often fine, and the fix is to find them in the playback list, enable them, and make them the default.
Fix it, in order
Check the physical connection. Make sure powered speakers are switched on and plugged in, and the audio cable is fully seated. Try a different port, and test the speakers on a phone or another PC to confirm they work at all.
Show disabled and disconnected devices. Open Settings, System, Sound, More sound settings, then the Playback tab. Right-click the empty space and tick Show Disabled Devices and Show Disconnected Devices. If the speakers appear greyed out, right-click them and select Enable.
Set the speakers as the default. In the Playback tab, right-click the speakers and select Set as Default Device. Windows can only send sound to one default output, and a monitor or headset that grabbed the default will silence the speakers.
Pick the right output in the taskbar. Click the speaker icon on the taskbar, then the arrow next to the volume slider, and select the speakers. This is the fastest way to check whether Windows is simply sending sound to the wrong device.
Run the audio troubleshooter. Open Settings, System, Troubleshoot, Other troubleshooters, and select Run next to Audio. It checks the default device, the services, and the driver, and can re-enable a device itself.
Reinstall the audio driver. In Device Manager, expand Sound, video and game controllers, right-click the audio device, select Uninstall device, and restart the PC. If Windows reinstalls a generic driver, install the audio driver from the laptop or motherboard maker's site instead.
Check for a monitor stealing the output. A monitor connected by HDMI or DisplayPort appears as a playback device, and Windows often picks it as the default. If only the monitor is listed, that is the cause, so set the speakers as the default and the sound will follow.
A green checkmark on the wrong device is the most common cause of silent speakers. Always check which device is the default before reinstalling drivers, since a driver reinstall cannot fix a wrong default.
If it still happens
If the speakers never appear in the Playback tab, even with disabled and disconnected devices shown, the audio device itself is missing from Device Manager. Follow the page on no audio output device being installed, which covers the driver and firmware steps for a device Windows cannot see at all.
Common questions
Why do my speakers work on my phone but not my PC? The speakers are fine, so the problem is on the PC side. The usual causes are a disabled playback device, a wrong default output, or a missing audio driver, in that order.
Only my monitor shows as a playback device. Where are my speakers? The monitor is an HDMI audio device and Windows picked it as the default. Show disabled devices in the Playback tab, enable the speakers, and set them as the default.
Speakers are enabled but still silent. What now? Check the volume in the taskbar and in the app itself, then restart the Windows Audio service. If the speakers test fine in the Playback tab with the Test button, an app is sending sound to the wrong device.