I NEVER told you to go beyond deleting the mentioned folders in YOUR HOME
directory, ie /home/sibu_rajappan directory. If you went that far as to even delete /usr/share/apps/switches/gnome-session, even deleting important files in /etc and even in /root user directories, I'd rather say you reinstall the gnome itself (no, no need to reinstall Linux, this isn't windows). Look for thread on installing rpm files.
The idea behind it, let say you create a new user called 'linux_admirer' with useradd command, in Redhat it will create a new user namely 'linux_admirer' and make a directory 'linux_admirer' under /home directory (so it becomes /home/linux_admirer). If you 'ls' the directory content, there will be no files with the '.' (dot) yet (or at least only one or two files, I think .bashrc and .bash_profile will be there). This is also true for other applications. Then you open your GNOME session for the first time. It would create the folders (the ones that I asked you to delete) and create the default settings for you. Then as you change the GNOMe up to your taste, it would be saved in those directories. Sometimes (or at least for me it often happens), you messed up the settings just like in case you exit the GNOME without properly saving the settings or force reset, usually you will have problem opening your GNOME session. That's when you have to delete all those messed up settings so that it would create a new default one for you. That's the real theory behind it.
But sibu_rajappan, don't be so frustated with trying/playing with different things/settings in Linux, and end up messiong up things, its just the beginning. I messed up my Linux many times before I get used to it. Good Luck.
If you still have the files mentioned (i.e. .nautilus .metacity .gconf* .gnome*) in your /root directory, you can try using it. Copy it to your home directory (assess it first with root account):
su - [password]
cp -R /root/.nautilus* /root/.metacity* /root/.gnome* /root/.gconf* /home/sibu_rajappan/
chown -R sibu_rajappan:sibu_rajappan .metacity* .nautilus* .gnome* .gconf*
Exit root account.
Then try using your account again to start GNOMe session.
May be I misunderstood your post saying that you deleted the files in /root.