When an item is declared "missing" in LEO, we have already searched for it twice a week for 3 months and still not found it in the building. Sometimes the item will turn up after we've labeled it as "missing," but it is rare. Every six months, items that are listed as missing are reviewed by the subject liaisons who decide whether we should purchase a replacement copy. The library may sometimes buy an updated edition or an alternative title on the same topic.
If you would like to speed up the replacement of a specific "missing" item, please inform the Acquisitions Librarian who will try to replace it right away. If your time frame is very short, you might want to utilize Interlibrary Loan.
Contact the Acquisitions Librarian at duncancj@jmu.edu.