Sometimes reopening a sales order involves more than simply reopening a closed line item. When a sales order goes through the entire process of having its stock being issued to shipping, an invoice is then created and posted. With the invoice finalized, the sales order is then marked as 'closed'. This is the sales order process for the most part, but in some cases of reopening a sales order, backtracking through this entire process is necessary.
This process begins with voiding the posted invoice. In order to open an already completed sales order for editing, you need be sure that the order's invoice is voided. Go to Sales > Customer > Workbench, enter the customer in the Customer # field, tab to refresh, and then select the Accounting tab.
Customer Workbench Receivables List
From here, under the Receivables radio button, select to show closed invoices, and right-click the invoice that corresponds with the order # you're trying to reopen. From the right click menu, choose to Void Posted Invoice. Note that voiding the invoice should create a mirroring credit memo so the balance becomes 0.00 rather than a negative amount.
Void Posted Invoice
Since the order's invoice has been voided, the next step would be to recall the order back to shipping. Go to Inventory > Shipping > Recall Orders to Shipping. Select the shipped order that corresponds with your order number, and select the RECALL button.
Recall Orders to Shipping
Next, go to Inventory > Shipping > Issue to Shipping. Since the order has been recalled, its stock will now be back in shipping. Enter in the order # and select a line item and click the RETURN STOCK button. This will return the order's line item stock and reopen the line item in the sales order.
Return Stock to Line Item
Once all of these steps are finished, go to Sales > Sales Order > Open Sales Order, and the order number should be back in that list.