WSKeys expire after three months of no use, and WSKeys are automatically deleted after 12 months without being used. An expired WSKey may be able to be renewed, but there is no way to recover a deleted WSKey.
If your WSKey is expired, and you need to renew it, follow the steps here to renew your key. If you are having trouble reenabling the key, contact OCLC Support with the key you are using.
If your key has been deleted, you will need to request a new one. See How to request a WSkey on the Developer Network site for more information.