localhost - Error "Sorry, I need a wp-config-sample.php file to work from. Please re-upload this file from your WordPress installation." -

i have been getting error while installing wordpress locally:

"error establishing database connection either means username , password information in wp-config.php file incorrect or can't contact database server @ localhost. mean host's database server down."

i searched web solution. people said check if mysql server online (mamp says is) or change wp-config-sample.php file.

// ** mysql settings - can info web host ** // /** name of database wordpress */ define('db_name', 'wp_demo');  /** mysql database username */ define('db_user', 'root');  /** mysql database password */ define('db_password', 'root');  /** mysql hostname */ define('db_host', 'localhost');  /** database charset use in creating database tables. */ define('db_charset', 'utf8');  /** database collate type. don't change if in doubt. */ define('db_collate', ''); 

i have done , still no avail. last step changing "wp-config-sample.php" filename "wp-config.php" netted me error:

"sorry, need wp-config-sample.php file work from. please re-upload file wordpress installation."

i using win 7, mamp 3.3.1 php 7.1.5. localhost on port 8888. mysql port 8889

change db_host localhost 127.0.0.1:8889