How to repair or replace built-in camera?

Recently, my built-in camera doesn't work and I have tried couple of method for diagnosis. I have updated the software for the webcam and it is still not showing up in the device manager. I sent it to technician for repair but they are scared of messing with the camera at the back of the screen and hence refused to repair. Apart from buying external webcam for my laptop, do anyone know or have a guideline to replace or repair the built-in camera? Sincerely, I appreciate if anyone can teach me on this. Thank you in advance.