Black screen after update was interrupted by laptop switching off [closed]

Solution 1:

Such a situation can come if the installation is stopped midway. Good news is that all your files are safe there. Also, during update all the required files were already downloaded to your laptop (otherwise installation would not have started.)

So, now you just need to complete the installation process. First, Ctrl+Alt+F1 (or F2, f3, f4 anyone is fine.) Then you would reach the linux console. Login with your username and password there. Then issue the following command:
sudo dpkg --configure -a

This should complete your update and your system should be back up after a reboot. If the above gives errors of broken packages, issue the below command:
sudo apt-get install -f

And then run the above command again.

P.S: Did you really mean Ubuntu 14.10 ? That's an alpha-release software, NOT meant to be used for daily use. You must switch to 14.04 as soon as possible.