Unable to import a module that is definitely installed

I had the same problem: script with import colorama was throwing and ImportError, but sudo pip install colorama was telling me "package already installed".

My fix: run pip without sudo: pip install colorama. Then pip agreed it needed to be installed, installed it, and my script ran.

My environment is Ubuntu 14.04 32-bit; I think I saw this before and after I activated my virtualenv.

UPDATE: even better, use python -m pip install <package>. The benefit of this is, since you are executing the specific version of python that you want the package in, pip will unequivocally install the package in to the "right" python. Again, don't use sudo in this case... then you get the package in the right place, but possibly with (unwanted) root permissions.

In my case, it is permission problem. The package was somehow installed with root rw permission only, other user just cannot rw to it!