I am going through the same problem. I ran sudo chmod 777 -R * in wrong directory (to make it worse the directory was root /). So I was unable to even login to ubuntu. It threw me back to login screen even when I am logged in. It also gave me a graphical popup message saying: Install error: the config details for GNOME power manager has not been installed correctly. Contact your computer Administrator.
Afte logging in (without letting me actually login) it gave me the error: there is problem with the configuration server. /usr/lib/libconfig2-4/gconf-sanity-check-2 exited with status 256

After a bit of research I did following:

in recovery mode root prompt I run following commands:

Code:
chmod 755 /etc/gconf/gconf.xml.system
chmod 777 /tmp
chmod 700 /home/my_user_id
chmod -R 700 /home/my_user_id
chmod 644 /home/my_user_id/.dmrc
After that I was atleast able to login to Gnome session with root user.
Now I tried to check user/group permissions but it gave me the error: can not open unknown error occured. Wired Network devices can not load at the boot and are not editable anymore, so obviously I am not able to connect to the internet. So I am not able to do important administrative tasks and Audio is also missing. Things like System Testing is also not working. Most things that involves some kind of special privileges are not working. I need some help as there are lot many softwares (including servers/websites) installed and I don't want to reinstall ubuntu (after taking lot of backup).

Even more research and through recovery mode root I changed /etc/sudoers permission to 0440 and was able to use sudo command in terminal but still administrative services are out of control.

I even tried to create new user but system denies to open services. So One thing I can do is to create new sudo su super user using terminal and can login with that user and change permissions in current user. Can someone tell me how to create new super user sudo user su using command line, terminal. OR

Can I restore my file permissions to default (0755/0644/0440 etc) by ubuntu.

Links to solution of the problem are okey...

Is it really necessary or compulsory to reinstall as it can be a lot of work for me. A whole week of extra work. (I don't even have backups ()