Is the date stored in the database as a string? That makes things a little complicated, but not impossible. You could select the date like this:
SELECT
CONCAT(SUBSTRING("13/07/2006", 7, 4),
SUBSTRING("13/07/2006", 1, 2),
SUBSTRING("13/07/2006", 4, 2)) AS 'new_date'
and ORDER BY 'new_date'