How can I reverse an invoice I've inadvertently voided?

I'm here to help you re-enter the voided invoice, @info-tewkesburys.

You can reverse the transaction by recreating it. Make sure that all details are the same from the voided one.

Here's how: 

1. Open your QuickBooks Online (QBO) account.
2. Go to the (+) New icon, then select Invoice.
3. Fill in the required details, then save the transaction.

To learn more about what happens when voiding or deleting transactions in QBO, you can open this article: Void or delete transactions in QuickBooks Online.

If you want to email or print your invoices in the future, you can use this article as your guide: How to email or print an invoice.

Post again if you have any other questions. I'm always here to help. Have a good day!