saving word files to PDF option will not remain in word program

First, a short explanation of what's what.

From your description, there might be some confusion between two different brands of PDF making tools in MS Word -- one tool by Adobe and another by Microsoft.

PDF Maker is an Adobe plug-in for MS Office programs, including Word. It's installed when Adobe Acrobat Pro or Standard is installed, so you can't install just PDF Maker by itself. It's part of the Adobe Acrobat "package."

However, you can turn the plug-in On and Off in Word's Options panel:

• File / Options (very bottom on left side menu) / Add-Ins

When installed and On (activated), there are 2 ways to export a PDF:

• Use the Acrobat Ribbon bar/tab at the top.
  
• Use File / Save As Adobe PDF from the File menu.
  

They both use the Adobe PDF Maker plug-in to convert the file, but I find there are more controls when using the Acrobat Ribbon method, especially if you need to make an accessible tagged PDF or one for printing.

A third way to export a PDF from Word is to use Microsoft's built-in conversion utility:

• File / Save As / and select PDF from the File Type drop-down menu. This method has nothing to do with Adobe.

In the above, note the wording: Save As Adobe PDF is not the same utility as Save As / PDF.  Which one were you specifically trying to use, Adobe's or Microsoft's? Your original post stated "in the past I have used File>save as pdf" which indicates you were using Microsoft's built in converter, not Adobe's.

Your situation:

Since you're getting the message, "Missing PDF Maker files", something's wrong with the installation. Either:

1. Acrobat itself was uninstalled (and along with it the PDF Maker plug-in files),
2. Microsoft Word was updated some time after Acrobat and its PDF Maker plug-in were installed,
3. The PDF Maker files were deleted from your computer, or
4. The plug-in has become corrupted.

Do you know if any of the above events happened?

If they did and you want to use Adobe's PDF Maker plug-in, you'll have to re-installed a licensed copy of Acrobat Pro or Standard so that it can add the PDF Maker plug-in to Word.  You can do this through the Adobe Creative Cloud manager, the red infinity icon:

1. After the manager apps opens, locate Acrobat and select UNinstall from the options.
2. Shut down your computer. (Full shut down so that it's "off", rather than a reboot.)
3. Restart your computer and re-launch the Creative Cloud manager app.
4. Locate Acrobat and select Install from the options.

This should clear up any missing or corupted files with your copy of PDF Maker.

Hope this helps.