No module named '_bz2' in python3
I found a pattern in those issue.
It happens mostly if you are missing dev tools and other important libraries important to compile code and install python.
For me most of those step did not work. But I had to do the following :

Remove my python installation

pyenv uninstall python_version

Then install all the build tools to make sure I am not missing any

sudo apt-get install -y make build-essential libssl-dev zlib1g-dev libbz2-dev \ libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \ xz-utils tk-dev libffi-dev liblzma-dev python-openssl git

Reinstall the new python version

pyenv install python_version
I hope that solves your issues.
When trying to execute the following command:

import matplotlib.pyplot as plt

The following error occurs:

from _bz2 import BZ2Compressor, BZ2Decompressor ImportError: No module
  named '_bz2'

So, I was trying to install bzip2 module in Ubuntu using :

sudo pip3 install bzip2

But, the following statement pops up in the terminal:

Could not find a version that satisfies the requirement bzip2 (from
  versions: ) No matching distribution found for bzip2

What can I do to solve the problem?