Ubuntu 16.04 does not show the login screen on booting

Question

My machine was working completely fine till I restarted it, and now I cant reach the login screen. After turning ON the machine I can reach the GRUB where I select Ubuntu, after which I get a black screen, where I expect a login screen to appear. I did check some other posts but none seemed helpful I haven't made any changes recently, I don't have a lot of experience with Ubuntu so any help would be appreciated.

Solution

Are you greeted with a black screen or terminal prompt?

If only a black screen -> enter the grub menu and highlight the Ubuntu option. Press the 'e' key and add the text nomodeset before quiet splash. The result should be nomodeset quiet splash, then press ctrl+x to load the OS. If this does fix your problem then at least you know it may be a video driver problem.

If you do get to a prompt (try 'ctrl+alt+F1' or 'ctrl+alt+F2', the GUI is usually on ctrl+alt+F7) you could try and start the login screen with sudo service lightdm start. If this does work you may have a different problem, maybe installing the display manager again will fix any errors. To install it type sudo apt-get install lightdm.

If starting the lightdm does not work you could try a more basic debugging option by typing startx at the prompt, perhaps this will help you shed some light on the problem.