Can not properly install blender

I think its time to give up. I installed Ubuntu 12.04 two days ago. and wasted 36 hours on finding solution here at askubuntu and other forums, following them more than 4 times reinstalled Ubuntu but its such a waste , not because Ubuntu is not good, because there are so many different information here, so confusing for newbies like me. so thought it's time to get back to windows, still I want to try one more time, this time I again reinstalled a fresh Ubuntu and here is what I want.

I want to run blender 2.69.

what I have.
⠀i7 processor with 3gb
⠀nvidia Geforce 640 with 4gb ram

what I did so far.

tried many follow up here on askubuntu. got some response to my help call too. but they just keep quiet after a few answers and leave me in the middle of nowhere, then I have installed fresh and follow again different suggestion. the one I found very easy to follow is this tutorial but the installation of Nvidia worked and the installation of cuda failed, again I installed Ubuntu fresh one, and started second time this time the first step installation of Nvidia failed.
now its fresh installation of Ubuntu.

Thanks for your response.

I have cuda 5, I dont know when I try to download there was more than one type
Ubuntu 12.04 DEB** RUN DEB** RUN DEB

I just choose RUN.

I want blender to use my Nvidia graphics card for better performance, once I installed blender and it was working but in preference > system I did not find GPU or my Nvidia option, it was just CPU, so I removed it,
for the link you provided I did not try that but I will try it and get back to you, if I can have your Skype would be nice, I will only bother you till my computer is up and running again properly with blender, :) thanks.
the link provided to download blender at the page on your given link does not exist, but I will download it from the main side if it's OK.

I followed your step at the provided link, but...

...it's not clear how to open blender application, anyway I went to the folder containing blender and clicked on blender.exe and found this error message:

Archive:  /home/shams/blender/blender.exe
[/home/shams/blender/blender.exe]
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on

  the last disk(s) of this archive.
zipinfo:  cannot find zipfile directory in one of /home/shams/blender/blender.exe

...or /home/shams/blender/blender.exe.zip and cannot find /home/shams/blender/blender.exe.ZIP period.

and when I try to run from the terminal

shams@ubuntu:~$ sudo cp ~/blender /usr/lib/blender -r
[sudo] password for shams: 

shams@ubuntu:~$ blender
The program 'blender' is currently not installed.  You can install it by typing:
sudo apt-get install blender
shams@ubuntu:~$ 

...so, should I use sudo apt-get install blender?

These are links to my screenshots from Blender and Additional Drivers:
⠀http://grab.by/s3K8
⠀http://grab.by/s3K0
⠀http://grab.by/s3K4
⠀http://grab.by/s3ME
⠀http://grab.by/s3N6

I have a new issue with my Nvidia GeeForce 640 on i7 processor
can somebody help please.
Thanks

here are some ouptu

shams@ubuntu:~$ /usr/lib/nux/unity_support_test -p
Xlib: extension "GLX" missing on display ":0.0".
Error: GLX is not available on the system
shams@ubuntu:~$ lspci | grep VGA

01:00.0 VGA compatible controller: NVIDIA Corporation Device 0fc1 (rev a1)
shams@ubuntu:~$

Blender is available in the Ubuntu Software Center. It will solve your problem if you install Blender using the Ubuntu Software Center. Alternatively you can also install Blender from the terminal by running the command: sudo apt-get install blender.

In order to install the recommended proprietary driver for your NVIDIA GeForce GT 640 graphics card, search in the Dash for Additional Drivers. Click on the Additional Drivers icon to open Additional Drivers. From the list of Nvidia drivers, select the driver that has [Recommended] after it. That's the graphics card driver that will give you the best performance. Click the Apply Changes button in the lower right corner to install the recommended Nvidia graphics card driver. Reboot to enable the Nvidia graphics card driver.

Here's how to enable CUDA with an NVIDIA graphics card. In Ubuntu 14.04 you need to install the nvidia-331 graphics driver or more recent in order to enable CUDA. You also need to install the NVIDIA CUDA runtime library. The Compute Unified Device Architecture (CUDA) enables NVIDIA graphics processing units (GPUs) to be used for massively parallel general purpose computation. Remove the existing proprietary NVIDIA driver and then open the terminal and type:

sudo apt-get install nvidia-331 libcudart5.5    

Update: The updated above command for Ubuntu 16.04 is:

sudo apt install nvidia-375 libcudart7.5

Then open Blender and select File -> User Preferences and it will open a Blender User Preferences window. As you can see in the screenshot CUDA is enabled in Blender in Ubuntu 14.04 with an NVIDIA graphics card that is similar to yours.