I found a solution. Running a
sudo apt purge nvidia-drivers-*
brought monitor back to being seen by the OS, but still not used right. The issue is that I had set the default gcc to be 5.5. I finally noticed that during installation of the nvidia-driver-470 (in my case) was running into an error building the kernel modules. I found here
that gcc must be version 7. So I set the gcc with
sudo update-alternatives --config gcc
to gcc-7, reinstalled the nvidia-driver-470, restarted, and all is well again.