How to clean-up / reinstall nvidia drivers on ubuntu 20.04?

nvidia-smi is failing:

$ nvidia-smi
NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.

There appears to be prior installation (attempts?) of nvidia on this machine. How do I clean this up?

$ sudo ubuntu-drivers autoinstall
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nvidia-driver-465 : Depends: libnvidia-extra-465 (= 465.19.01-0ubuntu1) but it is not going to be installed
                     Recommends: libnvidia-compute-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
                     Recommends: libnvidia-decode-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
                     Recommends: libnvidia-encode-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
                     Recommends: libnvidia-ifr1-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
                     Recommends: libnvidia-fbc1-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
                     Recommends: libnvidia-gl-465:i386 (= 465.19.01-0ubuntu1) but it is not installable
E: Unable to correct problems, you have held broken packages.