It was a rather simple solution - I'd got the shutter slide across. I hadn't realised it was there. Mea culpa.
I've just bought a used Latitude 7420. It came with Windows 10 Pro and I updated that to Windows 11 Pro. I didn't try the webcam prior to the update. Subsequently, I've tried using the webcam - tried using it for face recognition login, when the red LED by the camera blinked and the white LED also came on, but the image remained black, and with the camera app - once again the image remained black. I have checked the setting in the BIOS - webcam is enabled. I have uninstalled and reinstalled the drivers, and checked the privacy settings for the camera, and everything appears in order. Is there an issue with Windows 11 and the webcam, or is there something else I should try?
Latitude 7420 webcam not working