ubuntu18.04LTS for the first time can not start the problem

Solution

Enter tty2 interface alt + F3-F6 (F1 to enter the graphical login, F2 to enter the current graphical interface)
sudo APT the Remove --purge navidia- * # uninstalling navidia components
sudo apt purge gdm gdm3 # gdm3 uninstall GDM
sudo APT Ubuntu install gdm3 -desktop # install gdm
systemctl restart # restart gdm gdm