Can you upload a screenshot of Device Manager?
In Device Manager do you see ANY of these entries?
Microsoft Front Camera
Microsoft Rear Camera
Windows Hello Face Software Device
If nothing appears, then: Click View > Select Show hidden devices
If cameras still do not appear, Windows is not detecting the hardware.
Shut down the device
Hold Volume Up
Press Power
Release Power but keep holding Volume Up
You will enter Surface UEFI settings.
Check:
Devices → Camera
Make sure Front / Rear camera is Enabled.