Unplug the camera and restart your computer. When the computer reboots, try plugging the camera into a different USB port. Start the Camera app (Windows 10) or Photo Booth (MacOS).
You should be able to select the camera via the drop-down Camera menu (MacOS) or Settings menu (Windows).
If you can see the camera as an available video input, but still see a video input error message, you may need to enable the camera in your computer's security settings.
Windows 10 users should click the Start menu, then select Settings > Privacy > Camera. From here, choose your preferred setting for "Allow apps to access your camera". MacOS Mojave+ users should visit System Preferences > Security & Privacy and under the Privacy tab, click Camera. Then check the box next to the app you wish to use with the camera.
In most cases, plugging the camera into a different USB port and enabling it in your privacy settings is enough to cause the computer to recognize it, but if you still cannot see an image, or the image is defective in some way, please open a case with us.