Unable to reboot ubuntu 22.04

I am using ubuntu 22.04 lts. Recently, I installed lightdm for guest mode. After sometime I want to delete the guest mode, so I searched on internet. I made these changes in this file in terminal

/etc/ect/lightdm/lightdm.config

[SeatDefaults]  user-session=ubuntu   greeter-session=unity-greeter  allow-guest=false

After saving this file, I try to reboot the system, but it showing like this:

Keyboard Keys are not working. Please anyone tell me how to login to my system. I have many important files in my system.