The certificate on the Wireless Lan controller had expired.
I installed the certificate and restarted the controller.
The controller lost the entire user account database.
I imported the database from another system and after the reload the database was again lost.
Apart from this everything else works fine.
And there are also problems when restoring guest user accounts from Wireless Controll System, WCS the accounts are restored but not the passwords. Also we cannot set expiration date longer then 30 days, we have to set it unlimited first and then change it to limited.
Please let me know if anyone has come across this kind of an issue.