Uploaded file is broken

We used the free version of Download Manager to handle ALL of the PDF files on the website, and everything has been working fine with that since the site launched more than a year ago. All of a sudden, however, one of the most important and widely accessed PDF files on the whole site suddenly will not display. The URL is http://www.canyonhd4.org/download/meeting-calendar/?wpdmdl=771.

Every other file works fine but this one…. Click on any of the “Download” buttons on the Forms and Maps page (https://www.canyonhd4.org/resources/forms-and-maps/) and you can see what I’m talking about regarding all the other files working properly.

Please help!