Solution #1

If you don’t know or cannot find which process is using the webcam, the problem can be solved as follows:

1. Download and run the program Process Explorer (I recommend to run with administrator rights, in order to exclude possible problems with access rights).
2. Click on the binoculars icon (or simply the Ctrl+F key combination) to start the search.
3. In the input field, enter the query #vid.
4. Click the “Search” button.
5. In the list of results, click on a process that is not related to Skype (in principle, if something does not work, you can close all processes one by one, but as a first step I recommend disabling only foreign ones).
6. In the list on the left, a parent process will be selected that uses the webcam.
7. Right click on this process and select “Kill Process Tree”.
8. Start Skype and make sure that now you can make video calls.

Step-by-step instructions on how to find and close an application using a webcam:
Animated instructions on how to find and close an application using a webcam:

Solution #2

If the previous solution did not help, try this:

1. Download file WebCam_UpperFilters.reg
2. Open the reg-file and confirm that you want to make changes to the registry.
3. After the registry data is successfully written, restart the computer.