I have mistakenly configured this theme and now I can not access my server.

What did you do in the theme? You can start by changing the name on the theme’s folder so that WP uses a default theme – find the theme folder here:

wp-content
    themes
        customizr.HOLD

If that does not work, do the same thing – but for the entire plugins folder:

wp-content
     plugins.HOLD

Author can you please advice how can I get my server reactivated and work in this Theme?

This is what I have at present on my site: The website encountered an error while retrieving https://www.libseib.com/wp-admin/admin.php?page=LoginRadius&settings-updated=true. It may be down for maintenance or configured incorrectly.
Error code: 500

See what I posted above.

Do you mean in my server after logging in? Because I can hardly log in anymore

Where do I find the wp-content , before Customiz.HOLD?

You need to use FTP (or Cpanel) to access the files on the server – ask your hosting company for help if you don’t know how to do that. Also see:

https://codex.www.ads-software.com/FTP_Clients

Log in to your website through ftp.
Look in root of the website for a file called .maintenance and delete it.
See if problem is solved.

If not, delete the contents of /wp-content/upgrade.
See if problem is solved.

If not, rename your wp-content/plugins folder to wp-content/_plugins
If it’s solved, name it back and start renaming plugins (fastest way is to rename half) and see if it works. Than half of half, etc, till you find the one that has problems.

If not, rename your current theme folder. If it’s not this, you should probably backup your theme folder, reinstall WP and Customizr and see how you stand when activating your child theme again.

Hope I’m making sense to you.

Yes I am there now on the FTP Management. But this is what I got, can you advice further? Wp-content/themes/customizr /

Have you renamed the customizr theme folder as I posted above?

We I have tried every thing you told me to do but still in my FTP manager the Content can not be deleted. Yes to backup the theme could be a good idea but I am accessing it at all. The entire website and logging administration for wp is of line. I can log in with my username and password.I can only login on my hosting server

Your site seems to be working now.