Please find my answer to your questions below :
1) For most of the accounts I am getting 1969 as last login time?
Ujwol => Yes, that means either the password blob is not created yet..or the uer login tracking feature is not enabled in the password services.
2) Also if password was reset by identitymanager or by some other custom code than I think we won’t get this value…
Ujwol => Right. Only when CA SSO resets the user password , the password blob is updated. If there is any external password reset , it is not recorded in the ca sso password blob.
3) And what about changing the password through smjavaexpiry.java?
Ujwol => What is smjavaexpiry.java ? Can you clarify where did you find this ?