Facebook consistently scans the platform for pages and profiles which violate Facebook's Terms and Conditions. When a violation is found, the offending account or page becomes inactive or unpublished, depending on the situation. 

When a page is unpublished, administrators profiles still have the ability to see the page, however all non-administrator profiles are unable to view the content. 

When administrators look at the page, they should see a warning similar to:

This warning will be visible on desktop and mobile devices.

Republish Page

1. Log in business.facebook.com and click on the page that is no longer active.

2. Across the top menu bar, select "Settings."

3. Under "General", there is a menu item called "Page Visibility."

If you do not have a "General" tab, your profile does not have administrator privileges. Contact the web developer to have your permissions updated.

4. Select "Edit" on "Page Visibility"

5. Select "Page Published" and then "Save Changes."

6. The page will now be publicly available. 

For addition help, see the walkthrough video: