I upgraded my 14.04 Ubuntu to 16.04 today after I was prompted to on my home screen. It took a while to download and installation. But after installation step it shows that installation has failed and reverting to preview stage.
Then it crashed and I did a forced shutdown using the power button.
After this my laptop is not booting. It gets to the Ubuntu logo screen and thereafter screen becomes black.
On the top it shows
recovering journal 1223921 files of 3927642.
I tried command line login using Ctrl + Alt + f2 and it worked but when I run
apt-get update command it throws a relocation error that something is missing in