Not able to install k3b

This is perhaps a configuration issue. Do you have the 64 bits Ubuntu version?
What happens if you give this command in a terminal:

sudo apt-get install k3b

?

This is the output when given

hari@hari-desktop:~$ sudo apt-get install k3b
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package k3b
hari@hari-desktop:~$

Mine is a 32 bit system. I got the DVD from a magazine. I don't know whether its a 64 bit or 32 bit. How can we check it? I dont know how to check the medium. But knows only one thing its a i386 architecture.

I have inserted the DVD and have given the command and got the output.

Have you installed ubuntu on the HD or are you using the live CD?
Do you have an active internet connection while you using Ubuntu?

Ya I have installed the Ubuntu in the hard disk. I am not using the live CD. I have an active internet connection. But if you tell me to dowload something I may not be able to do so if the size is big. The speed is only 52 kbits/s .

I have tried the command
#sudo apt-get install k3b
from an active internet connection too.

Can you paste here the content of your file /etc/apt/sources.list ?

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb cdrom:[Ubuntu 7.04 _Feisty Fawn_ - Release i386 (20070418)]/ feisty main restricted
deb http://in.archive.ubuntu.com/ubuntu/ feisty main restricted multiverse
deb-src http://in.archive.ubuntu.com/ubuntu/ feisty main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://in.archive.ubuntu.com/ubuntu/ feisty-updates main restricted multiverse
deb-src http://in.archive.ubuntu.com/ubuntu/ feisty-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://in.archive.ubuntu.com/ubuntu/ feisty universe
deb-src http://in.archive.ubuntu.com/ubuntu/ feisty universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://in.archive.ubuntu.com/ubuntu/ feisty-backports main restricted universe multiverse
# deb-src http://in.archive.ubuntu.com/ubuntu/ feisty-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu feisty-security main restricted multiverse
deb-src http://security.ubuntu.com/ubuntu feisty-security main restricted
deb http://security.ubuntu.com/ubuntu feisty-security universe
deb-src http://security.ubuntu.com/ubuntu feisty-security universe

deb cdrom:[Kubuntu 6.06 _Dapper Drake_ - Release i386 (20060531)]/ dapper main restricted

Can you delete this line:

deb cdrom:[Kubuntu 6.06 _Dapper Drake_ - Release i386 (20060531)]/ dapper main restricted

from the file?
Have you been using (or are you using) a Dapper/6.06 CD?
Seems like you used the Ubuntu 7.04 CD to install and then used the Dapper CD to retrieve packages?
Post here also the output of these commands:

uname -a
cat /etc/issue

Ya I have deleted the line
deb cdrom:[Kubuntu 6.06 _Dapper Drake_ - Release i386 (20060531)]/ dapper main restricted
from it. I have tried to install KDE from that ie Y. I am using 7.04

hari@hari-desktop:~$ uname -a
Linux hari-desktop 2.6.20-15-generic #2 SMP Sun Apr 15 07:36:31 UTC 2007 i686 GNU/Linux

hari@hari-desktop:~$ cat /etc/issue
Ubuntu 7.04 \n \l

hari@hari-desktop:~$

I understand correctly that installing kde from the CD failed? Have you managed to install anthing from that CD?

Sir I have tried to install the KDE only . Nothing more. But I dont know how to install and so I didnt do anything more.
The problem is not with the KDE. Before that too I received the same error that

K3b cannot be installed on your computer type (i386). Either the application requires special hardware features or the vendor decided to not support your computer type.

I dont know why its so?

Sir its not only to K3b but to many s/w like Abi word, KOffice work space, Kword etc.........................

Can you paste here the result of these commands:

ls -l /var/lib/apt/lists/
cat /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_feisty_main_binary-i386_Packages | grep k3b

?

hari@hari-desktop:~$ ls -l /var/lib/apt/lists/
total 4612
-rw-r--r-- 1 root root 28599 2007-06-21 12:03 Kubuntu%206.06%20%5fDapper%20Drake%5f%20-%20Release%20i386%20(20060531)_dists_dapper_main_binary-i386_Packages
-rw-r--r-- 1 root root 1124 2007-06-21 12:03 Kubuntu%206.06%20%5fDapper%20Drake%5f%20-%20Release%20i386%20(20060531)_dists_dapper_Release
-rw-r--r-- 1 root root 189 2007-06-21 12:03 Kubuntu%206.06%20%5fDapper%20Drake%5f%20-%20Release%20i386%20(20060531)_dists_dapper_Release.gpg
-rw-r--r-- 1 root root 2077 2007-06-21 12:03 Kubuntu%206.06%20%5fDapper%20Drake%5f%20-%20Release%20i386%20(20060531)_dists_dapper_restricted_binary-i386_Packages
-rw-r----- 1 root root 0 2007-06-07 17:00 lock
drwxr-xr-x 2 root root 4096 2007-06-07 17:00 partial
-rw-r--r-- 1 root root 0 2007-04-09 19:13 security.ubuntu.com_ubuntu_dists_feisty-security_main_binary-i386_Packages
-rw-r--r-- 1 root root 0 2007-04-09 19:13 security.ubuntu.com_ubuntu_dists_feisty-security_main_source_Sources
-rw-r--r-- 1 root root 32439 2007-04-09 20:02 security.ubuntu.com_ubuntu_dists_feisty-security_Release
-rw-r--r-- 1 root root 0 2007-04-09 19:13 security.ubuntu.com_ubuntu_dists_feisty-security_restricted_binary-i386_Packages
-rw-r--r-- 1 root root 0 2007-04-09 19:13 security.ubuntu.com_ubuntu_dists_feisty-security_restricted_source_Sources
-rw-r--r-- 1 root root 4582827 2007-06-21 11:38 Ubuntu%207.04%20%5fFeisty%20Fawn%5f%20-%20Release%20i386%20(20070418)_dists_feisty_main_binary-i386_Packages
-rw-r--r-- 1 root root 24288 2007-06-21 11:38 Ubuntu%207.04%20%5fFeisty%20Fawn%5f%20-%20Release%20i386%20(20070418)_dists_feisty_Release
-rw-r--r-- 1 root root 191 2007-06-21 11:38 Ubuntu%207.04%20%5fFeisty%20Fawn%5f%20-%20Release%20i386%20(20070418)_dists_feisty_Release.gpg
-rw-r--r-- 1 root root 19796 2007-06-21 11:38 Ubuntu%207.04%20%5fFeisty%20Fawn%5f%20-%20Release%20i386%20(20070418)_dists_feisty_restricted_binary-i386_Packages
hari@hari-desktop:~$

hari@hari-desktop:~$ cat /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_feisty_main_binary-i386_Packages | grep k3b
cat: /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_feisty_main_binary-i386_Packages: No such file or directory
hari@hari-desktop:~$

For what I can see, you have only tried to install k3b (and the others) from CD. You failed because these are NOT on the CD.
You must have an active internet connection during install for apt-get to be able to fetch the packets from the repositories and install them.
I checked in.archive.ubuntu.com which is updated and on-line, so there is no reason why you should not be able to fetch them with an active internet connection.
To be sure, delete also this line from the sources.lst file:

deb cdrom:[Ubuntu 7.04 _Feisty Fawn_ - Release i386 (20070418)]/ feisty main restricted

First make sure you have a live internet connection, then clear the cache and resynchronise with:

sudo apt-get clean
sudo apt-get update