and fill these entries
db name wordspress
db user name: omsingh
db password : 123456abc
db host name : localhost
table prefix : wp_
you will find error inspite of that i am dead sure about field entries.
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.