Fix Unresponsive Contabo CWP VPS

My Contabo VPS (Linux) is still reachable through the VNC console, yet normal services (?) have stopped: websites no longer load and the CWP control panel won’t open. I haven’t touched the configuration or installed anything recently, so the root cause is unclear... (Budget: $10 - $30 USD, Jobs: Apache, Linux, MariaDB, Nginx, PHP, System Admin, Troubleshooting, Web Hosting)