I tried pretty much every solution posted here. I am running Elementary 0.4.1 Loki, and the day-before-yesterday i ran some updates trough the AppCenter, and these updates requred a reboot for some reason. After that reboot i couldn't log in. What finally solved the problem for me, after trying everything else posted here i did this - I ran the ecrypt-mount-...
At this stage it's not configurable and has been designed like that. I did see on Reddit quite a few remarks and suggestions regarding that same issue. Head over to teh sub-reddit here:
Create a new file /etc/lightdm/lightdm.conf and put the following in it:
Then, press CTRL+ALT+F1 to open the command line and execute service lightdm restart.
After that, you should have the option 'Manual login' at the bottom of the login screen.
sudo ubuntu-drivers autoinstall
Was the first step in what worked for me. That installed the right set of drivers and at least got me to a desktop, but it turns out that I could only get 640x480 resolution. After this, the nVidia Settings window comes up completely blank (except for Apply and Cancel buttons) and the native System Settings->...
An option to revert back is to use AppCenter > Installed, wait until the nvidia drivers become visible on the top, click on the icon of the one that is installed and then uninstall.
Using command prompt only, sudo apt purge nvidia-* or sudo apt remove nvidia-* . For the first command line option to work probably you have to install purge.