How can i back up my updated & installed packages & give me name of resumble software for installing updates fastly?

You can use GParted to resize your partitions. I suggest you defragment the partitions before resizing them. I also warn you that there's a chance data may be lost after the process.

How to Resize and defragment the partition?

Did you install using Wubi or did you resize your NTFS partition to make space for Ubuntu?

Can you give the output of:

lsb_release -a; uname -a; df -h; mount

Thanks

asif@asif-desktop:~$ lsb_release -a; uname -a; df -h; mount
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04.1 LTS
Release: 12.04
Codename: precise
Linux asif-desktop 3.2.0-29-generic-pae #46-Ubuntu SMP Fri Jul 27 17:25:43 UTC 2012 i686 i686 i386 GNU/Linux
Filesystem Size Used Avail Use% Mounted on
/dev/sda6 21G 3.0G 17G 15% /
udev 237M 4.0K 237M 1% /dev
tmpfs 98M 800K 97M 1% /run
none 5.0M 4.0K 5.0M 1% /run/lock
none 244M 80K 244M 1% /run/shm
/dev/sda3 47G 22G 26G 46% /media/Softwares
/dev/sda6 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
gvfs-fuse-daemon on /home/asif/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=asif)
/dev/sda3 on /media/Softwares type fuseblk (rw,nosuid,nodev,allow_other,default_permissions,blksize=4096)
asif@asif-desktop:~$

HEY.......i had upgraded packages and copied the upgraded packages from var/cache/archieves but after reinstalling ubuntu how can i install them back

I HAD NOT RESIZED PARTITION for installing but i have created new partition for Ubuntu......and i installed it using wubi

Your system is only using 15%

/dev/sda6 21G 3.0G 17G 15% /

So you have plenty of space to play with. Are you still wanting to remove Ubuntu?

NO i dont want anymore space but........I WANT TO REINSTALL UBUNTU 12.04 so plz tell me how to backup the packages and install them after reinstalling.....

The debs will be in /var/cache/apt/archives unless you have told apt-get to clean them out.

Yes they were there, but not installed on my system.....how to unpack them?

Why would you need to unpack them? They can be used to reinstall apps without having to redownload. No unpacking needs to happen in any way

Yes reinstalling ...... how it is done

You can use:

sudo dpkg -i filename.deb or glob using:
sudo dpkg -i *

you can also double click deb and it will install.