Hi and Happy New Year!
Please try this:
– rename “hide_my_wp” plugin folder name under /wp-content/plugins/ directory
– set htaccess content to WP default (https://codex.wordpress.org/htaccess)
– change permission of htaccess file to read only
– login to wp-admin
– rename back “hide_my_wp” plugin to it’s original name
– activate HMWP plugin
– click on “reset settings to WP” button in HMWP start tab
– change htaccess file’s permission to 644 or 755
– now apply “medium privacy” settings from HMWP start tab.
If it’s still the issue, then please let us know your website’s wp-admin login details and FTP details (as private reply), so that we can fix it for you.