Terminal is not opening after python3 installation

I installed python 3 in my ubuntu 16 version by following the given tutorial http://ubuntuhandbook.org/index.php/2017/07/install-python-3-6-1-in-ubuntu-16-04-lts/

After installation i can not open my terminal. I tried switching to virtual terminal by using CTRL+ALT+F2 but there is nothing. There is no terminal just a blank window. I have tried rebooting ubuntu using CTRL+ALT+F1 into virtual console but it does not restart. it just gets stuck at ubuntu startup screen.