A method and a system for unlocking a storage device that has become locked or cannot be unlocked are disclosed. A hint is generated from a key by removing bits and adding bits. A position of removed bits, a position of added bits, the number of removed bits and the number of added bits are stored and known securely. When the key cannot unlock a storage device corresponding to the key, the position of removed bits, the position of added bits, the number of removed bits (N) and the number of added bits are retrieved. Then, the added bits are removed in the hint. Each possible N bits are placed in the hint at the position of removed bits to generate 2N possible keys. Then, each of 2N possible key are tried to unlock the storage device.