Please let me know which user and in which client you want to unlock?
You can logon to the system like this-
User name: idadmin
Then after logon to the system reset the password of those users you want using SU01 tcode.
If you can't do this also then I will tell you how to reset sap* user's password.
If all the users are locked then, login to Database access the table USR02 and delete the entry of SAP* of specific Client and then logn to SAP to that particular client by using password pass.
if only one user is locked then log on the Other user or SAP* with the specific password and unlock the login user ID.