I am new to alfresco and using alfresco community edition 4.2b. I had already integrated apache directory studio with alfresco. when i login with ldap user in alfresco it logs in successfully but is not able to change his password, it is not any change password option in alfresco.
If you are using LDAP to manage user credentials, that is where the password change needs to happen. Alfresco doesn't have the password–it lives in LDAP.
Most people who use a central directory also have a central web app where users can make changes to their profile or their password. Is that the case for you?