WordPress Database Error Fix on Unmanaged Verpex VPS

I need a WordPress/server specialist to fix a site that is currently showing “Error establishing a database connection.” The issue began after the server ran out of disk space. I deleted some large backup files, but the site is still failing on subpages and may have database-related problems. Verpex support confirmed that the VPS is unmanaged and suggested database repair/optimization, but I need someone to actually diagnose and fix the issue properly. Support also mentioned: repairing and optimizing the WordPress database, checking for high resource usage, reducing stuck/excessive WordPress processes, and potentially restarting or recovering the database service if needed. What I need: Diagnose the root cause of the database connection issue. Check whether the database is corrupted or needs repair. Confirm whether disk space or server resource exhaustion caused the problem. Restart/recover the database if necessary. Get the WordPress site back online. Provide a brief summary of what was fixed and any prevention steps. Ideal freelancer: Strong WordPress troubleshooting experience. Comfortable with unmanaged VPS/server issues. Experience with MySQL/MariaDB, cPanel, and WordPress database repair. Able to work independently and communicate clearly. Please include: Relevant experience with WordPress database errors. Whether you can work with unmanaged VPS hosting. Your estimated turnaround time.