I am sorry that I forgot the files from dmesg and Xorg.0.log. And right after sending this bug report I read some articles in AskUbuntu. I installed Ubuntu by UEFI mode when the bug happened, and I found no use of UEFI for me. Then I reinstalled by Legacy mode and meantime I erased everything when I found email from here. I regret why I didn't put those files on Google drive or somewhere...
I am sorry that I forgot the files from dmesg and Xorg.0.log. And right after sending this bug report I read some articles in AskUbuntu. I installed Ubuntu by UEFI mode when the bug happened, and I found no use of UEFI for me. Then I reinstalled by Legacy mode and meantime I erased everything when I found email from here. I regret why I didn't put those files on Google drive or somewhere...