I at present have a lot of video players on my Windows 10 PC, about a dozen of them, including VLC for Windows and Media Codecs Pack. None of them will play most of my videos. The problem formats are (I know they are connected): mp4, mpeg, vob. Also avi is unpopular. WindowsMediaPlayeris supposed to play vob is it not, it always opens in Play With when I click a file but then says the file is not supported. All the other players produce similar notifications.
What is going on?