Fix WordPress DB Connection Error

My WordPress site on Network Solutions suddenly shows “Error establishing a database connection.” The issue started right after I uploaded a new theme and upgraded both PHP and WordPress to their latest versions. Since then I can reach the wp-admin area only sporadically; most of the time it times out with the same database error.

I need someone who can dive into the wp-config.php settings, check the database credentials, repair any corrupted tables if necessary, and make sure the site and dashboard load reliably again. Please keep the existing content and settings intact—no data loss, no theme resets.

Deliverables (acceptance criteria)
• Front-end pages display normally without database errors
• wp-admin is fully accessible every time
• A short summary of what was fixed and any preventive steps I should take

Experience with cPanel/phpMyAdmin on Network Solutions hosting and solid MySQL troubleshooting skills will be a big plus. I’m ready to get this resolved right away.