This was an issue that I just had and sorted out but I thought I would post my experience here to help anyone suffering the same fate:
I updated my recent install of Elyssa through the mintupdate, a bunch of 3's which I didn't really look too closely at. I was surprised there were so many updates since Elyssa just came out but no big deal.
On next boot after the initial Linux Mint boot bar, the screen goes BLACK and nothing would get me out of it except hitting the restart/poweroff button on my computer.
On next boot I noticed I was booting into a new kernel on the Grub menu by default. The old kernel was still there as an option. I guess my kernel got updated on that last update. I figured then it was something to do with X.org not working, and more specifically my Nvidia restricted driver, since I think they use kernel headers which need to match your current kernel.
What to do?
Well, boot into the old kernel version, where everything works, and disable or uninstall your restricted drivers. Restart, boot into the new kernel (should work now, although the video resolution may look funny). Install the driver you just got rid of ( I used Envy to install the Nvidia driver), restart when finished and that should take care of it.