Tkinter module not found on Ubuntu

What worked for me in Ubuntu was actually just:

sudo apt-get install python3-tk

For python 3.6:

sudo apt-get install python3.6-tk

I didn't read anywhere, I simply tried it, as onteria_'s method didn't seem to work for me.

The answer to your question is that Tkinter is renamed to tkinter in python3.

That is with lowercase t.

In python 3 Tkinter renamed tkinter