Thanks William,
When I has the line
#DAVLockDB /var/run/davLocks/DAVLock
in the httpd.conf, then my server-manager and other pages work ,
But the problem which still remains is that now i cannot see any listings of the svn repositories in the conf file, which were there previously.
Because of that all the repositories could not be accessesed over https and I this is causing a lot of problem among our developers (users).
The snapshot of the subversion page on my server-manager is
Please see that whether the options for modDav are okay or not.
Also as you can see in this image I have given https access and alos authentication required yes .
Thanks and Regards
Hasan