WP doesn't work after updating to version 3.2.1

I updated Word Press to the new version manually.

The PHP version on my hosting server was also updated to 5.3.

But couldn’t login to the wp-admin page and got the following error:

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 example.net. 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

Then the hosting company downgraded PHP to 5.2.6 and tried to login again, but the got the following error:

pply_filters( ‘wp_list_bookmarks’, $output ); if ( !$echo ) return $output; echo $output; } ?> PHP Parse error: syntax error, unexpected ‘=’ in D:\hshome\example\example.com\blog\wp-includes\class.wp-styles.php on line 120

Is Word Press 3.2.1 not compatible with certain versions of PHP?