When cancelling or refunding an item, in an order, it is possible to choose whether or not you want to return the ordered quantity to stock. This can be actioned in 2 ways, either from the main order tabs or within an edit order screen.
Within 'Open Orders' and 'Awaiting Dispatch' tabs etc, ticking a line(s) and selecting the status 'Cancelled' or 'Refund' will display an extra tick box for 'Return Quantity To Stock'.
When editing an order, ticking a line(s) and selecting the status 'Cancelled' or 'Refund' will display an extra tick box for 'Return Quantity To Stock'.
Important - If you have deleted the option set of an item or archived a product, it is still possible for you to choose to 'return to stock' on that product. The item will not be returned to stock.