If an order was archived either accidentally or intentionally in Sales & Success Center, there is no option to specifically "un-archive" the order, however, you can convert the archived order to a draft, which will then give the option to resubmit the order.
To do this, follow the steps below:
Step 1: Log in to the Sales & Success Center or impersonate a Salesperson from Partner Center.
Step 2: Navigate to Orders, (on the left navigation panel).
Step 3: Filter by "Archived" > Click on the Order. The 'Covert To Draft' button will appear at the top right of the order details page (screenshot below).
Step 4: Select Submit Order and it will re-create the order with a "Resubmitted" tag