There are several factors that can cause your webcam to not work properly:
Before attempting anything else, try using an alternative browser such as Mozilla Firefox, Internet Explorer or Google Chrome.
You can test your webcam here https://www.onlinemictest.com/webcam-test/
Too little light
The room is too dark and the computer may be slow. To solve this, make the room brighter and make sure you have a light in front of your face. Dark colours take more hardware resources (even for video recording) to process, so it requires more of your computer.
Too many applications accessing the webcam
You are trying to do the webcam test but you cannot see an image of yourself, or you only see a black screen. If you have other applications open at the same time, and one of them is using the webcam (such as Skype), you will not be able to proceed. Please shut down all other applications and restart your browser. The Sonru application should now be able to pick up your webcam.
If the hardware is not working you can first try to Update the Drivers for the webcam. If this still does not solve the issue, you will unfortunately have to replace the webcam.
Hope this will help, but otherwise please visit support.sonru.com and submit a request.