How do I reverse a closed sales order/invoice/payment?

Thanks for giving me the details of your concern about closed sales orders, invoices, and payments in QuickBooks Desktop Accountant 2021. I can definitely assist you in reversing them.
 
You can reopen this closed Sales Order in your QuickBooks Desktop, and this process will unlink from the invoice that is currently associated with it. Then, you'll need to delete the existing invoice and create a new one based on the reopened Sales Order.
 
Please note that any previous payments made on the original invoice will remain recorded in your account. You can apply for these payments as credits towards your future transactions. You can refer to the steps below together with some screenshots for better reference:

Proceed to recreate the invoice for a Sales Order:

1. Go to the Sales Orders main tab, and select the Create Invoice button.

2. On the prompt that appears, choose:

• Tick Create invoice for all the sales order(s) to add all items from the sales order to the invoice.
• Click Create invoice for selected items if you want to put only some items on the invoice.

3. Make the necessary changes in the Invoice.

4. Pick Save & Close.

For more details, refer to this article: Create an invoice in QuickBooks Desktop.

I'm adding these articles with the topics you can use while recording the common vendor and customer transactions:

• The Vendor Transaction Workflows in QuickBooks Desktop.
• The Customer Transaction Workflows in QuickBooks Desktop.

By following these steps, you should be able to effectively reverse the entire sales order, invoice, and payment process in QuickBooks Desktop Accountant 2021 to accommodate the returned items and address the update issue. If you have more questions about your sales orders in QBDT, don't hesitate to send a reply below. I'd be sure to answer them for you at any time possible. Have a great day!