Try the following steps until the issue is resolved: 
  1. Go to Merchandise > Merchandise search.  Make sure you are marking the box to include inactive.  Search for the item.
  2. If the status of the merchandise item is inactive, click Mark merchandise active under Tasks.
  3. Under the Inventory tab, see if the SKU itself is marked inactive.  Look at the Active column.  If it says No, click on the SKU and click Mark Active.