sudo service lightdm stop # to kill the user interface process
sudo apt purge nvidia-* # to remove all nvidia packages
sudo dpkg --get-selections | grep nvidia # check that no nvidia packages remain
sudo add-apt-repository ppa:graphics-drivers/ppa # if you still didn't add it
sudo apt update
sudo apt install nvidia-375 # installed the NVIDIA drivers v.375.66
sudo apt install nvidia-prime nvidia-settings # Probably already installed
sudo apt install nvidia-cuda-toolkit # if you want to use CUDA
sudo apt install nvidia-modprobe