If it is lost which appears to be the case, if company cannot find then you have no hope in finding it.
Once past expected delivery date buyer should open a NOT RECEIVED CASE, you refund through the case and then make a claim on I assume Packlink if that is who you used. PACKLINK delivers nothing, best to deal direct and cut out the middle men, or use Royal Mail, their Tracked 48 is a reasonably priced service with cover up to £150, far better than Courier’s £20.