Move your logic into the sql statement, clean up your code....

cleaner code with a decode

FUNCTION get_printed_status
RETURN varchar2 IS

  v_order status orders.printed%TYPE;
  v_status varchar2(30);

BEGIN

  SELECT decode(printed, null, 'NOT PRINTED'
                       ,    0, 'NOT PRINTED'
                       ,    1, 'PRINTED'
                       ,    2, 'ON HOLD'
                       , 'UNKNOWN')
  INTO   v_status 
  FROM   orders
  WHERE order_no = p_order_no;

  RETURN v_status;
END get_printed_status;