If your webcam isn't detected anywhere — not just in one app — the issue is almost always permissions, a driver, or another app holding exclusive access, not failed hardware. Work through these in order.
1. Check system-level camera privacy settings
On Windows, go to Settings > Privacy & security > Camera and confirm "Camera access" is on, and that the specific app you're trying to use is allowed. On Mac, go to System Settings > Privacy & Security > Camera and check the same. This is the single most common cause of "not detected" that's actually just a blocked permission.
2. Check if another app is using it
Most webcams only support one application accessing them at a time. If you have Zoom, Teams, or another video app open in the background — even minimized — it can hold the camera and block other apps from detecting it. Fully close other video apps and try again.
3. Check Device Manager (Windows)
Open Device Manager and look under Cameras or Imaging devices. If your webcam shows a yellow warning icon, right-click it and choose Update driver. If it's missing entirely from the list, try Action > Scan for hardware changes.
Tip: for an external USB webcam, try a different USB port, ideally avoiding a USB hub — some webcams need more power than a hub reliably provides, which can cause intermittent detection failures.
4. Test it in the built-in camera app first
Before troubleshooting in Zoom, Teams, or another specific app, test the camera in Windows' built-in Camera app or Mac's Photo Booth. If it doesn't work there either, the problem is system-level, not specific to one app — which changes where you should focus troubleshooting.
5. Uninstall and reinstall the driver
In Device Manager, right-click the camera, choose Uninstall device, then restart your computer. Windows typically reinstalls the driver automatically on boot. This resolves driver corruption that a simple update doesn't always fix.
6. Check for a physical privacy shutter or switch
Some laptops and external webcams have a physical sliding cover or a hardware switch to disable the camera. It sounds obvious, but it's a genuinely common cause that gets overlooked, especially on laptops where the switch is small or easy to bump accidentally.
The bottom line
A webcam that's not detected anywhere is almost always a permissions or driver issue, not hardware failure. Check system-level camera permissions first — it's the most common cause and the fastest to rule out.