Can't seem to get my login screen back after installing slim

At one point I switched from GDM to slim and now I can't seem to get past the splash screen. After pressing Esc I can see that it is stuck on Starting X Display Manager: Slim. I need to get back to GDM or just figure out what it is doing.

Thoughts?

From ubuntu nyxtom

• Assuming GDM is still installed:

  sudo dpkg-reconfigure gdm
  

  will let you select what your default display manager is. If it's not installed...well, install it.

  It'll go into effect on reboot.

  From maco

• I would drop into a command prompt - You can switch at any time by pressing Ctrl+Alt+F2 and login. Then you can sudo apt-get remove slim. Once you've done so - if you already have GDM installed then just sudo dpkg-reconfigure gdm otherwise run sudo apt-get install gdm

  From Marco Ceppi