I tried to install the nvidia driver for my card 2 or 3 times and every time it causes my Desktop, Icons and Launch bar to disappear and I had to reinstall Ubuntu.
How can I install it correctly? And if this problem happens again how can I uninstall the driver ?
You need to install the right driver. Not all drivers from Nvidia's site work properly on 12.04. When I was on 12.04, I tried several, until one worked. I don't know if they updated the drivers since.