Hello there, solace-marine.
Thanks for reaching out the Community. I'm here to help restore a deleted invoice in QuickBooks Online (QBO).
Restoring a deleted invoice would be a great option in QBO. However, this hasn't been made available within the program.
You'll want to recreate the deleted invoice. To get the detailed information of the invoice, you can use the Audit Log.
Then, recreate the invoice as new with its original transaction date using the information from the Audit Log.
For further guidance, you can refer to this article: Restore deleted transactions.
These steps should help you restore a deleted invoice by recreating it.
Please let me know if there's anything else you need. I'm here to help. Take care and have a great day.