Hi @barryreesrsa,
A 500 server error indicates an error with the server when trying to display your website.
If you have access to the Apache server logs in your website hosting control panel you may be able to find the 500 error and get an extended error message that offers more detail on what the cause is.
Often it will relate to incorrect file or folder permissions, corrupted .htaccess file, running out of PHP memory and more.
If you google you’ll find there are many articles available with step-by-step guides to help resolve 500 errors with WordPress. Some examples that may be helpful:
https://www.mhthemes.com/support/fix-500-internal-server-error-wordpress/
https://www.elegantthemes.com/blog/tips-tricks/how-to-fix-the-500-internal-server-error-on-your-wordpress-website
Often a 500 error is caused by a conflict with a newly updated plugin. If you can log in via FTP or use your web control panel you can move all of your plugins out of the wp-content/plugins folder temporarily. This has to be done carefully so that you can move then back in afterwards but moving them and visiting your admin backend will automatically deactivate those plugins resolving the conflict.
From there you can carefully move the plugins back into your wp-content/plugins folder and start activating them one at a time to find the plugin that is causing the conflict.
Please also check with your web hosting company and see if they are able to provide you direct support for this as part of your hosting package.