If you are using the Search bar to find your Order, you need the Customer Name, Email Address, Event Name or Reference Number. If the Order doesn't appear after this, then you may need to check that the details are correct.
If you are using the Orders page, then you may have it in the wrong filter. Use the Filter bar to ensure that the Complete box is ticked.
If you are trying to find an order for a Reserved Seating event, then you can find orders via the seat hover on the Venue Plan.