Some more info plse Julie Head.
The default install has no password on MySQL. I don't think you're getting that far, as you're asked for a password at http://localhost/
, which suggests an htpasswd issue. That address takes you to the XAMPP welcome page, IF it's still a default setup/install.
How fresh/default is the XAMPP installation? Many changes?
Is the prompt a pop-up 'Authentication Required' or the phpMyAdmin login?
The former is a htpasswd validation, run by Apache. The latter is php code run by the phpMyAdmin website, and connecting you to MySQL.