It seems to be that Windows has screwed up the file association for pdf files on your computer, so it's trying to use the wrong program to open it with. (Windows is well-known for messing up its file associations!)
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If you know that you've ALREADY got a pdf viewer on your computer, such as Adobe Acrobat Reader, Foxit or Sumatra PDF (and you're happy to continue using it), do the following:
Click the Search button at the bottom left of your screen. Start typing 'default'. When you see 'Default apps' appear above it, click on it.
Scroll down to, and click on, 'Choose default applications by file type'.
Scroll down to .pdf and click on the entry to the right of it.
Under 'Choose an application', click on the software that you want to use for opening PDF documents.
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If you've NOT already got a suitable app (or you'd like to use a better one), simply download and install Sumatra PDF:
https://www.sumatrapdfreader.org/free-pdf-reader
Windows should then
automatically use it to open PDF files. If it doesn't, follow the instructions above to tell Windows to use it.