Lost Nvidia drivers on 14.04

I have been trying to install Theano on my Ubuntu partition on a Dell Vostro laptop. It requires Cuda for using the gpu.

But I seem to have lost the Nvidia drivers somehow.

lspci -vnn | grep -i VGA 

gives this

00:02.0 VGA compatible controller [0300]: Intel Corporation Core
Processor Integrated Graphics Controller [8086:0046] (rev 18) (prog-if

00 [VGA controller])

so the Nvidia driver isn't listed. Also it is no longer listed in "Additional Drivers"

sudo apt-get install nvidia-current

gives

Reading package lists... Done
Building dependency tree       
Reading state information... Done
nvidia-current is already the newest version.

So, what am I missing?

Update:

lspci -k | grep -EA2 'VGA|3D'

00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 18)
  Subsystem: Dell Device 044f
  Kernel driver in use: i915

Update:

When I rebooted I got a black screen so I guess the drivers were lost. From the boot command line I did manage some reinstall of dirvers following this page. This did enable me to get back in the nvidia drivers weren't appearing in additional drivers.

Although I did try I tried in vain to resinstall the binary drivers. I decided I had to do a complete reinstall of my Ubuntu partition.

Having done this the nvidia drivers are now appearing in additional drivers.

drivers

What does it mean that it is using the X.Org server? Does that mean it is not using the Nvidia GPU?

Update:
I tried

sudo apt-get update
sudo apt-get purge nvidia-current nvidia-updates

Got "Unable to locate package nvidia-updates" so did

sudo apt-get purge nvidia-current
sudo apt-get install nvidia-340 libcuda1-340

But when I reboot I just get a black screen.

I've learned that if you do ctrl+alt+f1 at this point you get a terminal screen.

I managed to get back to the gui by these commands from here.

sudo apt-get update

sudo apt-get dist-upgrade

sudo apt-get install build-essential

sudo apt-get install linux-source

sudo apt-get install linux-headers-generic

sudo apt-get dist-upgrade

sudo reboot

sudo apt-get install nvidia-current-updates

sudo nvidia-xconfig

sudo reboot

But they remove nvidia-340 and libcuda1-340.

I tried again with

sudo apt-get purge nvidia-current

sudo apt-get install nvidia-340 libcuda1-340

and

sudo nvidia-xconfig

sudo service lightdm restart

But this remains on the black screen. So I am back to square one.

Update 2016.07-30:

sudo apt-get update

sudo apt-get purge nvidia*

sudo apt-get install libgles1-mesa libgles2-mesa libosmesa6 libva-drm1 libva-egl1 libva-glx1 libva-tpi1 libva-wayland1 libva-x11-1 vainfo libegl1-mesa libegl1-mesa-drivers libgbm1 libgl1-mesa-dri libgl1-mesa-glx libglapi-mesa libwayland-egl1-mesa libxatracker2 libvdpau-va-gl1 libdrm-intel1 libdrm2 libva1 va-driver-all i965-va-driver intel-gpu-tools

sudo apt-get dist-upgrade

I ran these commands, though without va-driver-all as I got this error,
E: Unable to locate package va-driver-all

On reboot the graphics came up ok and additional drivers showed using NVIDIA binary driver 340.96 (proprietary tested)

So that seems to have worked, thanks. Though there are still problems with cuda, but have asked another question for that here.