Hello,
Thank you for the reply. I gave up back then but now as you replied, I tried it again and something was different than last time. I don't know why or what changed it. First, as mentioned before, my system is Windows 10 Pro. When I started the Camera app, it didn't complain anything but showed my face just fine. My system settings has an "Apps & Features" item, and behind that, there is an "Optional features" item. I'm guessing it corresponds to your "Optional Apps". It shows that I have "Windows Media Player" installed, but I was not able to locate "Windows Media Pack" there.
This time, also Windows Hello Face setup starts and shows a video of my face. Below the video, there is a text saying "Make sure your face is centered in the frame." and below that, "Cancel" is the only button available. If I recall correctly, that was the case also last time before the setup stopped working entirely. Now, when I tried centering my face in the frame, I noticed every now and then a square (sometimes it's a grid) appears around my face in the video and a line attempts to start drawing along its top border line. Apparently something goes wrong or something, because the line never finishes the entire square (I'm assuming that's what it's trying to do, maybe more buttons would become available at the bottom if the line were able to finish the square). I tried adding more background light but I think it didn't have any impact on how far the line was able to proceed around the square. A lot of times the square or the line does not even appear and all I see is just a plain video of my face, no matter how I try to position my face in the video. I think the plain video was all that ever happened back then last time before the setup broke.
So, something is different from last time, but there is still a problem. Would anyone be able to help me out from this?