Amazon Simple Storage Service
Developer Guide (API Version 2006-03-01)

Return Code for Lost Data

If Amazon S3 detects that an object has been lost, any subsequent GET, or HEAD operations, or PUT Object copy operation that uses the lost object as the source object, will result in a 405 Method Not Allowed error. Once an object is marked lost, Amazon S3 will never be able to recover the object. In this situation, you can either delete the key, or upload a copy of the object.