After a power cycling activity, all the ports were inactive of some vtp client switches. As seen in the cisco doc http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080890613.shtml#topic10, this is a common issue when the native VLAN is not VLAN 1 for VTP client switches, need to follow the troubleshooting steps as in the document.
But it could see that, we were not able to enter into the enable mode using the local user id and password configured. We had to braek the password and once done, we see that none of the config was lost including the local username and password.
What could be the reason behind, the switches were not taking the enable password ?