Make sure you have the correct username and password, if you are sure you have the correct login and pasword, then you need to check with your administrator because you seem to have either the wrong login id or password and that's why your script cannot connect to your mysql database.

check these four things to make sure you have them right:

1. your hostname (Make sure your database is on the machine you are trying to run the php from and is configured for"localhost")
2. your database username (not your hosting username, BUT your mysql)
3. Your database password
4. Your database name
5. your port is the same port as used in command line.