14.04 keyboard and mouse stopped working at login screen

Solution 1:

This post doesn't ask a clear question, but the title is exactly what happened to my machine, albeit running ubuntu 16.

I had upgraded, and while the box booted to the lightdm login screen, keyboard and mouse (laptop internal, also I tried plugging in usb) were non-responsive. After a time the cursor in the password field stopped blinking as well.

It appears some X packages had been incorrectly deleted when i ran an apt autoremove (necessary due to a full /boot drive).

re-installing apt install xserver-xorg-input-all fixed the issue for me.

(to install this, boot into recovery mode, enable networking, and drop into the root shell. When completed, reboot.)