If an order was archived either accidentally or intentionally in the Sales and 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 an option to resubmit the order.
Here is how;
Step 1: Log in to the sales and success center or impersonate a Salesperson
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