WHMCS Reinstall and Restore

I'm facing data corruption/loss with my current WHMCS installation. I have a recent backup from within the last month, but I need help with reinstalling WHMCS and restoring the backup. The data that needs to be restored includes a database backup and the configuration.php file.

I have a VPS cPanel setup

When going to my domain I get a message that states Critical Error Could not connect to the database

Ideal Skills:
- WHMCS installation and configuration
- Data restoration from backups
- Server management
- Troubleshooting and problem-solving

Experience:
- Prior experience with WHMCS is a must
- Proven track record of data recovery
- Server management experience