How can i fix if pip3 is not working after instalation?

Question

I was trying to install matplotlib but first I had to install pip in MobaXterm and I think something failed.

I did:

python -m ensurepip

apt-get install python3-pip

Here I didn't want to, but I closed MobaXterm.

Then I tried starting again and I got:

Found package python3-pip
Package python3-pip is already installed, skipping

But then, when I try to install matplotlib:

pip3 install matplotlib

And I got:

Traceback (most recent call last):
  File "/bin/pip3", line 7, in <module>
    from pip import main
  File "/usr/lib/python3.4/site-packages/pip/__init__.py", line 13, in <module>
    from pip.utils import get_installed_distributions, get_prog
  File "/usr/lib/python3.4/site-packages/pip/utils/__init__.py", line 22, in <module>
    from pip._vendor import pkg_resources, six
  File "/usr/lib/python3.4/site-packages/pip/_vendor/pkg_resources/__init__.py", line 36, in <module>
    import plistlib
  File "/usr/lib/python3.4/plistlib.py", line 65, in <module>
    from xml.parsers.expat import ParserCreate
  File "/usr/lib/python3.4/xml/parsers/expat.py", line 4, in <module>
    from pyexpat import *
ImportError: No such process

Thank you and sorry, I'm really not an experienced programmer.