The usual

Error message on web:
Error establishing a database connection! This probably means that the connection information in your wp-config.php file is incorrect. Double check it and try again.
Are you sure you have the correct user/password? Yes, edited wp-config.php
Are you sure that you have typed the correct hostname? Yes, edited wp-config.php
Are you sure that the database server is running? Yes, confirmed by MySql Administrator
What is the next thing to check?
TIA