sudo apt purge python3-pip  
sudo rm -rf '/usr/lib/python3/dist-packages/pip'  
sudo apt install python3-pip   
cd
cd .local/lib/python3/site-packages
sudo rm -rf pip*  
cd
cd .local/lib/python3.5/site-packages
sudo rm -rf pip*  
python3 -m pip install --user xlwt