Upgrade fine except for one node

I was actually surprised at how easy it was to follow the directions and manually upgrade Drupal.  All went well, and in 10 mins the site was up and running again. 

However, I’m just noticing that ONE LONE PAGE seems to be totally completely dropped off the site, except for the text.  It has nothing on it, no theme, no header, the source code when I look at the page is just two lines within <p> tags. 

This used to be a page that accessed the database and pulled out some glossary terms with definitions.  I don’t know if perhaps this bork is caused by calls to mysql that were in the code?  Something weird like that?

In any case, any thoughts about how to get that page back?  I tried going to the node within the “Content” list but that doesn’t even work, as it doesn’t pull up a “node, edit, revisions” or anything…just a white page with two lines of plain text.

I would love to know if anyone knows how to get this working again or whether I have to simply redo it all.  And of course, if anyone knows WHY it might have dropped out (when all the other pages were fine!) that too would be great to know.

Thank you in advance!

Drupal version: 

Source: https://www.drupal.org/taxonomy/term/21/feed