Question covers my problem.
Windows Key + R and entering "%ProgramFiles%\LibreOffice\program\soffice.exe" (incl. double quotes) doesn’t start LibreOffice? Or are you talking about “Double click on a LibreOffice file doesn’t start LibreOffice any longer” or is it about “Click on the desktop link of LibreOffice doesn’t start the application” … more actions and failures possible. That’s in fact your title doesn’t fully cover your problem. Please edit your question and elaborate your problem.
Throw out that Microsoft trash and install an open-source operating system like Linux or BSD. This will solve your problem and many other problems, too.