It may happen due to xf86-input-mtrack I installed from AUR package. After that I followed this tutorial "https://howchoo.com/g/mdy0ngziogm/the-perfect-almost-touchpad-settings-on-linux-2" from second point. And then I used this command in terminal
sudo systemd restart gdm.service
, as much as I can remember. After that screen flashes for long time , so I force shut down my laptop. From then it is giving this problem. Though it used to show these ACPI errors before, but I was able to boot into the OS.