Word & PDF files not opening under Catalina

If you have any non-subscription version of MS Office earlier than 2019 you'll need to upgrade to Office 365 or the Office Home and Student 2019 versus.

As an alternative to Word try opening the Word file with the free, open-source LibreOffice app.

If you have a Catalina compatible MS Office try the following:

1 - Log into another admin user account, Set up users, guests, and groups on Mac,  and see if the problem persists. (This tells us if the problem is limited to your user account or is system wide).

2 - boot into Safe Mode (How to use safe mode on your Mac - Apple Support) by booting with the Shift key held down and check there to see if the problem persists.  Reboot normally and test again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing some system cache cleaning, volume verifying and directory repairing. 

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

IMPORTANT:

Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:

Also click and read the About info to further permit full disk access.

Then we can examine the report and see if we can determine what might be causing the problem.

Office for Mac 2011 is not supported by Catalina.

You can use this link to try finding an App that will open your docs.

https://support.apple.com/guide/mac-help/open-microsoft-office-documents-mchlp2737/mac

What version Office are you using to open Word documents?