Users can restore deleted Invoices by just clicking on the Restore button. Please follow the below steps to restore deleted Invoices; 

1. Go to the Invoice section
2. Select Trash from the secondary filter from the drop-down arrow. 
3. Now select the Invoice to be restored by clicking on the edit button. 
4. After selecting Invoice click on the Restore button and that's it Invoice will be restored. 

Please check the screenshot for more information;

-Moon Invoice