WordPress -Error establishing a database connection

My host auto-installed wordpress for me. So, I went to index.php on my ftp program to edit it –> which made me go to blog-header.php so i could edit the css/layout of the blog. However, it said that wordpress wp-config.php :
(“There doesn’t seem to be a wp-config.php file. I need this before we can get started. Need more help? We got it. You can create a wp-config.php file through a web interface, but this doesn’t work for all server setups. The safest way is to manually create the file.”, “WordPress › Error”);
}

$wp_did_header = true;

require_once( dirname(__FILE__) . ‘/wp-config.php’);

wp();
gzip_compression();

require_once(ABSPATH . WPINC . ‘/template-loader.php’);

endif;

?>
^ thats what it said.

So then I went to wp-config.php and edited all of the information and uploaded it to my ftp account. but when i went to blog-header.php it still didnt work so i deleted wp-config-sample.php but it still didnt work. then i dont remember what i did, i think i just went to wp-install.php and i think thats where i got my error because i think i reinstaleld it or something. so i clicked ‘install’ even though it already said wordpress installed. and then went i went to my actual site it said:
WordPress

Error establishing a database connection

This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down.

* Are you sure you have the correct username and password?
* Are you sure that you have typed the correct hostname?
* Are you sure that the database server is running?

If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.

^ any ideas on how i can fix this?

**also, when my host first installed wordpress it was fine. it looked like the standard wordpress blog. it was just that blog-header.php said ididnt configure wp-config.php so after i changed that i think something happened.