If you are facing an issue with the MySQL server being down in WHM (Web Host Manager), there are a few steps you can take to resolve it:

1. Check if the MySQL service is running:

- Log in to WHM with your root credentials.

- Go to the "Service Status" section in the main menu.

- Look for the "MySQL/MariaDB" service and check its status.

- If it shows as "down," try restarting the service.

2. Restart the MySQL service:

- In WHM, navigate to "Restart Services" under the "Restart Services" section.

- Look for the "SQL Server (MySQL)" option and click on it.

- Click the "Yes" button to confirm the restart.

3. Verify the MySQL server configuration:

- Go to the "Configuration" section in WHM and click "Tweak Settings."

- Look for the "SQL Server" tab and review the settings.

- Ensure that the MySQL server is configured correctly, including the allocated memory, timeouts, and other relevant options.

- Make any necessary adjustments and save the changes.

4. Check the error logs:

- In WHM, go to the "Server Configuration" section and choose "Apache Configuration."

- Click on "PHP Error Log" to view the logs.

- Look for any recent errors related to the MySQL server.

- If you find any specific error messages, search for solutions based on those error codes or messages.

5. Consider server resource limitations:

- A lack of resources like memory or CPU can cause MySQL to crash.

- Check the server's resource usage in WHM, focusing on memory and CPU.

- If you notice high usage in either category, consider optimizing your applications or upgrading your server resources accordingly.

6. Contact your hosting provider:

- If you've gone through the above steps and cannot resolve the issue, contacting your hosting provider is best.

- Provide them with detailed information about the problem, the steps you've taken, and any error messages you encountered.

- They should be able to provide further assistance or take appropriate actions to fix the MySQL server issue.

It's worth noting that these steps assume you have access to the WHM control panel and root privileges. If you don't have the necessary permissions, consider contacting your system administrator or hosting provider for assistance.