Free Software to Decrypt Windows CREDHIST File by Nirsoft

If you are looking out for a method to find out your old Windows password in hashed form, then this is the right tool for you

The CredHistView software decrypts the CREDHIST file and shows its contents including the hash of the stored passwords, after you login with the current password. 

Apart from the password hash, you will also see other details such as Guid, record index, iteration count, user SID, SHA1 Hash, hashing algorithm used, NTLM hash, and more