I started 4 the first time and there is no desktop or panel,also there is no konsole or some other programs. Restart doesn't help.

1st you need to specify distribution and version as well as the version of kde 4, also is this a new Linux install or an upgrade from kde3

how did you start kde 4?

do you have Gnome or other environment installed and running ?

Other useful information might be

What kind of video card do you have?

What exactly do you see when you start up? Describe the screen.

google01103 wrote:1st you need to specify distribution and version as well as the version of kde 4, also is this a new Linux install or an upgrade from kde3

how did you start kde 4?

do you have Gnome or other environment installed and running ?

I am running Ubuntu 11.04. I'm not sure how KDE got on my system, but it shows up as an option when I log in.
I have Nvidia GeForce graphics. I do have GNOME

annew wrote:Other useful information might be

What kind of video card do you have?

What exactly do you see when you start up? Describe the screen.

I have Nvidia GeForce graphics. When I start it and after it load I see a black screen

maybe you don't actually have KDE installed just an entry in gdm, follow this http://www.psychocats.net/ubuntu/kde to install KDE onto your Gnome install if you wish to ensure you actually have KDE available

A mate of mine has Mint and the same happened to him. I managed to fix it with the following command followed by a reboot:

sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak

I installed PC-BSD 8.2 yesterday on my old IBM Thinkpad T42 and am facing the same issue of missing Plasma Panel. Also, I cannot add it through Add Panel option.

@deepakrao: Have you tried deleting your Plasma configuration without Plasma running to see if that fixes the issue? It is very rare that you are not able to re-add a panel.

Are you sure that Plasma is running?