First Advice - Avoid NVidia, the company are not Linux Friendly.
Remove Nvidia driver that fails and start over
sudo apt remove --purge *nvidia*
nouveau - complete rubbish if you have any intention of gaming
You can try drivers from this PPA, but it didn't help me
sudo apt-add-repository ppa:graphics-drivers/ppa sudo apt update
You can remove it
sudo apt-add-repository --remove ppa:graphics-drivers/ppa sudo apt update
If it is still there
ls -l /etc/apt/sources.list.d