Many programs suddenly stopped working properly

[inexplicabro]

If I open a video on my PC, my video player (MPV) opens up but says "Drop files or URLs to play here". A similar message appears when I try opening the video with MPC-HC (curiously this doesn't happen on VLC). If I open a text file on Notepad++, instead of opening the file in question and showing me what's inside of that file, it opens up a new text file, as if I just ran Notepad++ straight from the Start Menu and not from opening a text file.

If I try using the windows context menu to extract a zip file using 7zip, instead of extracting said zip file, 7zip opens up without doing anything, as if I opened it from the Start Menu. If I click on a Chrome shortcut to Whatsapp Web, instead of going to that site it instead just opens the New Tab in Chrome. 

These are 4 examples of the problems I'm seeing. This has happened for many other applications, and so far 7zip is the only one that fixes it when I reinstall it (mpv worked for a while before reverting to the issue). Because of this pattern, I think the part of windows that gives commands to applications to do a particular action is broken, so instead, the programs just open up as if opened without any command.

I've tried sfc /scannow but it says there are no problems, I've tried uninstalling the most recent windows update (which was a long time before this problem started happening), reinstalling to the latest windows update but it still doesn't fix it. Any help would be appreciated.