Cannot login to websphere admin console? Maybe you forgot to start LDAP?

Cannot you login to IBM Websphere administration console and you have not changed the admin password recently?  Then a tipical reason is that LDAP user registry has been not started before to start Websphere. Check on the server SystemOut.log if there is this exception below:

com.ibm.websphere.wim.exception.WIMSystemException: CWWIM4520E The 'javax.naming.CommunicationException: your_ldap_hostname.com:389 [Root exception is java.net.ConnectException: A remote host refused an attempted connect operation.]' naming exception occurred during processing.
at com.ibm.ws.wim.adapter.ldap.LdapConnection.getDirContext(LdapConnection.java:1568)
at com.ibm.ws.wim.adapter.ldap.LdapConnection.search(LdapConnection.java:2731)
at com.ibm.ws.wim.adapter.ldap.LdapConnection.checkSearchCache(LdapConnection.java:2699)
at com.ibm.ws.wim.adapter.ldap.LdapConnection.search(LdapConnection.java:2889)
at com.ibm.ws.wim.adapter.ldap.LdapConnection.searchEntities(LdapConnection.java:3100)
at com.ibm.ws.wim.adapter.ldap.LdapAdapter.login(LdapAdapter.java:2695)

Example of resolution with the IBM Tivoli Directory Server as LDAP server:

1) Restart the db2 database if stopped:
su -dbinstanceuser
db2start

2) Restart the Tivoli Directory Server 6.3 if stopped:

cd /opt/IBM/ldap/V6.3/sbin
./ibmdiradm -I dbinstanceuser
./idsslapd -I dbinstanceuser

3) Restart Websphere