Ubuntu – Keyboard not working after suspend to ram (sleep)

I was able to fix the problem by adding usbhid.quirks=0x04D9:0xA0CD:0x20000408 to kernel boot parameters as described here https://unix.stackexchange.com/a/280574/41667.

Basically, run this in a shell to confirm you are applicable to this solution:

dmesg | grep i8042

and confirm you get this output

[ 1.514469] i8042: PNP: PS/2 Controller [PNP0303:KBC,PNP0f13:MOUE] at 0x60,0x64 irq 1,12
[ 1.525273] serio: i8042 KBD port at 0x60,0x64 irq 1
[ 1.525287] serio: i8042 AUX port at 0x60,0x64 irq 12
[ 1.526035] input: AT Raw Set 2 keyboard as /devices/platform/i8042/serio0/input/input3
[ 21.927438] input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio1/input/input10

then, add the boot parameters i8042.direct and i8042.dumbkbd to /etc/default/grub. For example, run

sudo nano /etc/default/grub

Find the line that begins GRUB_CMDLINE_LINUX_DEFAULT= and edit it to include the new parameters, so that after your edit it looks something like

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i8042.direct i8042.dumbkbd"

Save by pressing Ctrl+O, exit by pressing Ctrl+X, and run

sudo update-grub

Source: Some time traveler here on Ubuntu Forums