How to remove unmet dependencies in ubuntu
 

I am using ubuntu 12.04 and now when I open terminal and give command "sudo apt-get install build-essential" then it throws error complaining some unmet dependencies and asks me to run "sudo apt-get install -f" which wants 101Mb of data but I did not have speed for this much of data. Is there any other way which works without internet.

If you have unmet dependencies you will need to install them to get the initial package to install and work as intended. If you cannot download it from the internet you will have to purchase or borrow the full set of CDs or DVDs and install from them. The only other way is to get someone who does have fast internet to download all the packages you need for you using an application like keryx.

there must be some way put,Is there any undo option?

You are going to have to be a little bit clearer with what you mean. The first part of your sentence doesn't make sense.
"Is there an undo option?" For what? If you want to install something that needs other packages and you choose not to install it then just stop the installation process. How can you undo something you haven't actually done?

1) "Undo build-essential" : sudo dpkg --purge build-essential


2) Installing the required build packages,
that build-essential was going to install :
All those packages could be downloaded on another computer,
and then installed. Move all new packages to a new folder.
And : sudo dpkg -i new-folder/*
I.e. dpkg will find out the install order itself.
( All packages can also be achieved from a DVD set
http://www.osdisc.com/cgi-bin/view.c...s/linux/ubuntu )

The packages are : ( I may have forgotten some.)
linux-libc-dev libc-dev-bin libc6-dev make m4 patch autoconf automake
libtool autotools-dev libltdl-dev
binutils base-files xz-utils cpp-4.6 gcc-4.6 g++-4.6 libstdc++6-4.6-dev

.

thanks:)