I think to troubleshoot your problem you should try the following:
Check whether the MySQL service is running (Control Panel --> services)
Use a MySQL client like SQLYOG to check whether you are able to connect to MYSQL Server with the username and password you are using in your code.
Just try a sample php program, which fetches the data from table
Ex. http://www.anyexample.com/programming/php/php_mysql_example__display_table_as_html.xml