I have a fairly old LG laptop (circa 2007) that I have been running Lubuntu on. It is a lighter-weight version of Ubuntu, that uses the LXDE desktop rather than Gnome. Performance is reasonable with it. Anyway, since this is sort of the guinea-pig of all my systems, I thought I'd upgrade it to the latest version of Lubuntu (my other systems are still on the 12.04 LTS releases).
The upgrade went pretty smoothly, it has to be said. It was only when I got to the login screen and tried to type my password that things went wrong - I couldn't type anything. None of the keys worked, not even Control or F1, so I could switch to a text console. The touchpad and left/right click buttons were still working, and the keyboard still worked in the Grub boot menu.
A bit of head scratching, and plugging in a separate USB keyboard allowed me to type again. But that isn't quite an optimal solution. A bit of Googling led me to the following bug report for someone else with an LG laptop. Going by the eighth comment in that, it turns out a couple of options have to be added to the grub menu, by editing the /etc/default/grub file. In my case, the file had the following line:
I added two options to the end, so it became:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i8042.nopnp=1 i8042.dumbkbd=1"
Saved the file, and ran sudo update-grub to let the changes apply, and rebooted. I am now typing this blog post on the working laptop keyboard!