Fix MySQL PHP Connection Error

I have a PHP-based website that suddenly stopped talking to its MySQL database. Every page that relies on data now throws a connection error, so visitors see nothing but an ugly message. The rest of the codebase is stable; it’s purely the database hand-shake that’s broken.

Your task is to dive into the existing PHP, identify why the connection fails, and deliver a clean, working fix. Once repaired, the site should load data normally without warnings or deprecated notices, and your solution must stay compatible with the current server stack (PHP 7.4 on Apache, MySQL 5.7).

Deliverables
• Updated PHP file(s) with the corrected connection logic
• A short note outlining the root cause and the exact change made so I can maintain it later

I can provide SSH or cPanel access and the current config details as soon as we start. Let me know your turnaround time and any questions you need answered before jumping in.