I have an Ubuntu 14.04 system, on which I want to install OpenCV and use it with Python 2.x.
I installed OpenCV using the instructions here: https://help.ubuntu.com/
I think you don't have the python-opencv
package.
I had the exact same problem and
sudo apt-get install python-opencv
solved the issue for me.
you can install opencv from the following link https://www.learnopencv.com/install-opencv3-on-ubuntu/ It works for me . apt-get install doesnt contain many packages of opencv