Go to the below link and download the WMVCore.dll file:
wmvcore.dll free download - DLL-files.com
wmvcore.dll download - free dll files
Then, place the WMVCore.dll file in C:\Windows\System32\. Then, reboot your system for changes to take effect.
If still doesn't work, then open Elevated Command Prompt and run the below command:
When you hit Enter, it will register the dll in Windows. Then, try to open Webcam Manager application.