Fix WordPress Homepage Display Issue

My several month old WordPress site was running perfectly until three days ago; now the homepage shows only part of its content (lins at the top) while every other page still loads as expected. I have not installed new plugins or changed any settings during this time, and no error messages appear on the front-end or in the dashboard. The only alert I see is WordPress recommending several updates—core, themes, plugins, and an upgrade to a newer PHP version—which I have not applied yet.

What I need today is a clear diagnosis and quick remedy:

• Identify why the homepage sections are missing (theme conflict, outdated PHP, cached build, database issue, etc.).
• Restore the full homepage layout without disrupting the rest of the site.
• Safely handle any required updates, including PHP, with a rollback plan in case something breaks.
• Provide a brief summary of the steps taken so I can maintain the fix in the future.

You’re free to use standard debugging tools—cPanel, phpMyAdmin, WP-CLI, or any preferred staging workflow—as long as the live site remains online. I’ll supply WordPress admin and hosting credentials once we agree on the approach.