How can I re - open an invoice that I closed by mistake?

Hi there, nicholenetolmay-.

Welcome to the QuickBooks Community. Let me help you in reopening an invoice that was accidentally closed. Then, to ensure that the sales entry will link to the correct payment.

There is a Sales page in QuickBooks that provides you with a list of all the invoices that have been created. With this, you can go to the said section and locate the closed invoice from there. Then, delete the payment connected with the entry to unlink and reopen the invoice.

Here's how:

1. Open your QuickBooks Online (QBO) account.
2. Go to the Get paid & pay and choose Customers.
3. Click the customer's name and proceed to the Transaction List tab.
4. Locate and select the invoice to open its details.
5. Click the 1 payment made link under the Payment Status. Then, select the date. 
6. On the Receive Payment page, scroll down to the Outstanding Transaction section. Then, unlink the invoice by unchecking the box.
7. You'll be prompted with a message stating You didn't select any invoices. Then, you can click the Save as credit button.
8. Select Save and close. Then, click Yes to confirm.

Once done, you'll be able to see that the invoice is tagged as Open. Then, the payment appears as Unapplied. That said, you can open this article to see various details on how you can use the available credit for any customer's entry: Handle a customer credit or overpayment in QuickBooks Online.

Additionally, you can click this article to view detailed steps on how to apply and record invoice payments correctly: Record invoice payments in QuickBooks Online.

Lastly, you may refer to this article on how you can enter invoices that become uncollectible by recording them as a bad debt and write them off: Write off bad debt in QuickBooks Online.

If you have any other questions about reopening the invoice in QuickBooks, let me know by adding a comment below, nicholenetolmay-. I'm always here to help. Keep safe!