Hello Mk, there is no option to recover a deleted invoice. You can use the Audit log as your guide to re-create the entry.
To access it, start by clicking on the gear icon located in the top right corner of your screen. Once you’re there, select the Audit Log option. In the Events dropdown menu select Deleted or Voided transactions and then apply the correct date.

If you'd previously emailed the invoice to your customer, there's also a good chance you've got a PDF copy sitting in your sent emails, which can be handy as a visual reference while you're recreating it.
Please let us know if you have any additional concerns. We're here to help.