NVIDIA-SMI couldn't find libnvidia-ml.so library in your system. Please make sure that the NVIDIA Display Driver is properly installed and present in your system.
Please also try adding directory that contains libnvidia-ml.so to your system PATH
2.解決方法：
# BTW this is all in console mode (for me, alt+ctrl+F2)
# login + password as usual
# removing ALL nvidia software
$ sudo apt-get purge nvidia*
# Checking what's left:
$ dpkg -l | grep nvidia
# Then I deleted the ones that showed up (mostly libnvidia-* but also xserver-xorg-video-nvidia-xxx`)
$ sudo apt-get purge libnvidia* xserver-xorg-video-nvidia-440
$ sudo apt autoremove # clean it up
# now reinstall everything including nvidia-common
$ sudo apt-get nvidia-common
# find the right driver again
$ sudo add-apt-repository ppa:graphics-drivers/ppa
$ sudo apt update
$ ubuntu-drivers devices
$ sudo apt-get install nvidia-driver-440 # the recommended one by ubuntu-drivers
$ update-initramfs -u # needed to do this so rebooting wouldn't lose configuration I think
$ sudo reboot
