I'm trying to install pycrypto for python 3.x.x on raspberry pi
but when i run python setup.py install
from the command line, it is by default installed to python 2.7.x
i have installed python-dev and still with no luck, i have read that using a PIP might help, but unfortunately i don't know how to use it. all my codes are written for python 3.3.x  and it would take me a very long time to re-write them all for 2.7.
so how can i fix it without re-writing my codes
Having looked into it there does not seem to be a pycrypto version for python3 at the moment. I think you're options are to look for an alternative package or to convert your code to python 2. There are tools available which can do this automatically, for example 3to2 is available in pip.
how to install python package in Raspbian?