I was having the exact same problem with Ubuntu 12.10 on an Asus Eee pc 1225. I've had some trouble with
ACPI functions with this machine in the past. I'm no longer buying Asus products because they are poorly made.
Anyways, to fix this problem I added a boot parameter to GRUB. I found the suggested solution here:
Keyboard not working on a Samsung 300e5a laptop
I tried adding
acpi=noirq but that seemed to only re-enable the keyboard. The touchpad still didn't work. Next I tried
acpi=off. That worked to get both keyboard and touchpad working. I also tried
acpi_osi=Linux and that also worked. I tried rebooting and not changing the boot parameters and the keyboard and touchpad again didn't work. It only worked with
acpi=off. Your results may be different.
To change the boot parameters, check this link:
How do I add a kernel boot parameter?
Basically, when GRUB starts at boot, press E to bring up the editor. Find the line that starts with
linux and add
acpi_iso=Linux to the end of it, and then press Ctrl+X.
Then if that fixes your problem, make the changes permanent by editing the
/etc/default/grub file. Find the
GRUB_CMDLINE_LINUX_DEFAULT line and add
acpi_iso=Linux to the end of the value on the right. Save, run
sudo update-grub and reboot.
I hope that works out for you. Good luck.