couldn't login to Ubuntu18.04 with GUI

problem

• I accidentally removed libpng16-16:amd64 as shown below;
  sudo apt-get remove libpng16-16:amd64

• then my desktop gradually disappeared.

• I stopped the process and killed it.

  • I checked the process number and killed it with the command;

  ps ax|grep apt
sudo kill -KILL <process number>

• After I rebooted my PC, of course I couldn't login to my PC with GUI.

what i am doing

• log in the PC and installed ubuntu-desktop

sudo apt-get install ubuntu-desktop

now

• I could login to Ubuntu18 with GUI, but I cannot use Japanese Keyboard, now I am repairing.

reference

• https://blog.amedama.jp/entry/2018/08/04/230601