my .htaccess file content:
------------------------------------------------------
RewriteEngine On

# Don't rewrite any URIs ending with a file extension (ending with .[xxxxx])
RewriteCond %{REQUEST_URI} !\.[a-zA-Z]{2,5}$ [OR]
RewriteCond %{REQUEST_URI} \.(html|htm|php)$ [NC]
# Don't rewrite admin directory
RewriteCond %{REQUEST_URI} !^/myshop [NC]
# Don't rewrite editors directory
RewriteCond %{REQUEST_URI} !^/editors [NC]
# Don't rewrite cPanel directories
RewriteCond %{REQUEST_URI} !/cpanel [NC]
RewriteCond %{REQUEST_URI} !/frontend [NC]
# Handle all other URIs using Zen Cart (index.php)
RewriteRule .* index.php?%{QUERY_STRING} [L]
---------------------------------------------------------------

Try to open
xxx.com/xxxxx.html

but get 404 error page