Speaking as a subpostmaster I can advise as follows...
You will have been issued with a receipt that carries a unique code when you bought the order. Take it to any Post Office and they will be able to tell you if the postal order has been cashed you will need to complete a form P58.
Unless you asked for it to be crossed it will be able to be cashed at any Post Office and not necessarily paid into a bank account.
Either way the order is traceable.
HTH
