the login screen is not appearing after booting up

I tried stopping and starting the init.d but of no use...

It is Ubuntu 8.10

sudo dpkg-reconfigure gdm

then restart

https://help.ubuntu.com/community/VNC

You may not need a full desktop. Why do you need to see the full desktop? What are you trying to achieve by using VNC? Their may be a more graceful method that is not only lighter on the network but also secure (VNC has zero encryption)

By using the above command,
The output I got was
*Reloading GNOME Display Manager configuration
*changes will take effect when all current X sessions have ended
invoke-rc.d:initscript gdm,action "reload" failed

Regarding VNC, I do not know about it. I just want a software so that I can provide my friend remote access. If you know something which is quite good let me know.

And plz plz help me in solving this problem. I don't want to reinstall xubuntu again. i have some important softwares setup. So it would be hectic for me to install them again.

i would uninstall vnc, see if it helps.

Why does he need remote access? If he is accessing apps you can use x forwarding (for example). File access can be securely configured using sshfs and can be mounted when the user logs in as a local folder. I would not use vnc over the www as their is no encryption so any attacker can simply harvest the packets and see what is going on VERY easily.

if the uninstall vnc doesn't help, try:

sudo apt-get --purge remove gdm; sudo apt-get clean; sudo apt-get install gdm

I suggest you review why you need vnc, there is often a better solution. Especially over WAN

when i tried to remove VNC it showed me no such packages.
i used the command sudo apt-get remove vnc.

When I removed gdm it worked fine by removing the gdm.
but when I tried to install it using apt-get install gdm

it showed me error like Unable to retrieve package from us.ubuntu.package.com something like this.

could not resolve us.archive.ubuntu.com
Err: http://us.archive.ubuntu.com jaunty/main gdm 2.20.10-0ubuntu2
like wise i got three similar errors...

Are you using Ubuntu 9.04 ...? Please check by typing:

lsb_release -rdc

Thank you

No I am using Ubuntu 8.10

So you need to dress something into your /etc/apt/sources.list because some row a referring to Jaunty, Jaunty is the codename of Ubuntu 9.04

As we can see from the errors you get:

Err: http://us.archive.ubuntu.com jaunty/main gdm 2.20.10-0ubuntu2

Hope this helps

Ok so VNC is definately the culprit. If you are demoing the desktop remotely then vnc is great, for anything else there are much better options.

Ok. So What I need to do now??
Please let me know.

How are you installing the vnc server and which vnc server are you using?

This looks ok:

http://lifehacker.com/317125/set-up-vnc-on-ubuntu-in-four-steps

You may want to try this too:
http://stevenharman.net/blog/archive/2008/12/13/vnc-to-a-headless-ubuntu-box.aspx

You still haven't outlined why VNC is needed. Outside of screen presentation it really is superflouous in most cases.

I installed it by simply giving
sudo apt-get install x11vnc vnc-java
Then I have to do this:
       Set up a password for clients. Code: x11vnc -storepasswd
       Open up ports 5800 and 5900 on your firewall
       Run the terminal command: x11vnc -forever -usepw -httpdir /usr/share/vnc-java/ -httpport 5800 and add it for auto-starting in future sessions
the right steps for installing VNC on the server.

This is how i installed vnc in my system....

Please give me some solution.
Is Reinstalling ubuntu is the only option??

Why do you need VNC? Maybe it is not needed and all this is in vein. A reinstall will not yeild any gain as the system itself is fine

So, Now Wht my next step is?
I removed gdm but unable to reinstall it again.

when i tried to remove VNC it showed me no such packages.
i used the command
 sudo apt-get remove vnc.

When I removed gdm it worked fine by removing the gdm.
but when I tried to install it using apt-get install gdm i got error like

could not resolve us.archive.ubuntu.com
Err: http://us.archive.ubuntu.com jaunty/main gdm 2.20.10-0ubuntu2
like wise i got three similar errors...

This is the way I installed the VNC
http://lifehacker.com/317125/set-up-vnc-on-ubuntu-in-four-steps

This is for VNC https://help.ubuntu.com/community/VNC

About installing gdm and its errorsI think the repository was down or something wrong with your connection.

in text mode:

sudo apt-get update
sudo apt-get install gdm
sudo /etc/init.d/gdm restart

or

in text mode just type "startx"

i hope it helps