Good evening, Gudrun.
Thanks for joining us here in the Community. I'd be happy to help!
Once an invoice is voided, there isn't a way to undo it. You'll need to manually recreate the invoice by heading to the "Gear" icon and selecting the "Audit" log. From there, locate and click on the transaction that was voided. Gather all information, such as date, amount, customer etc. Next create a new invoice by clicking on the "+New" button and then "Invoice". Enter all the information you have gathered in order to recreate the voided transaction.
I can see how you would like to see the option to undo a voided transactions, so I recommend leaving feedback for our developers. Comments are viewed and considered as they create new features and updates for the software.
If you have any other questions, feel free to reach back out here.
