Upgrading ( please help!)

it is saying
Fatal error: Call to undefined function wp_register_plugin_realpath() in /home/content/48/11949948/html/wp-settings.php on line 213

Try:
– switching to the default theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

– resetting the plugins folder by FTP or phpMyAdmin.

– re-uploading all files & folders – except the wp-content folder and the wp-config.php & root .htaccess files – from a fresh download of WordPress. Make sure that you delete the old copies of files & folder before uploading the new ones.

– running the upgrade manually via wp-admin/upgrade.php

but how do i swich, where do i go? I went to WP.org /themes but there is nothing there ??

You need to do this on your site.

that’s the problem…
Every time I try to open insanelydivine.com it’s giving me this page

Fatal error: Call to undefined function wp_register_plugin_realpath() in /home/content/48/11949948/html/wp-settings.php on line 213

so i dont know where to go from there. It says Call but who do i call?

Try:
– switching to the default theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

– resetting the plugins folder by FTP or phpMyAdmin.

– re-uploading all files & folders – except the wp-content folder and the wp-config.php & root .htaccess files – from a fresh download of WordPress using FTP. Make sure that you delete the old copies of files & folder before uploading the new ones.

– running the upgrade manually via https://your_site/wp-admin/upgrade.php

Oh – and Call to undefined function is a technical programming term. It does not refer to phoning anyone.

i went to back up support it says…
‘Back up your database regularly,and always before an upgrade.’
i think i didn’t back up before i clicked the upgrade button…
have I lost everything? :((((

Hopefully not. Right now, you simply seem to have an incomplete upgrade.

please help…im already having palpitation….
how do i even open something…

Please carry out the steps I suggested above. We do not have access to your site, so there is nothing we can do from our end. The work has to be carried out on your site. If you cannot manage this yourself, you may want to consider hiring someone.

again, i can’t access my site. its giving me the same fatal Error
im already looking for one to hire.
Thank you for your time