I was upgrading Ubuntu 11.10 to Ubuntu 12.04 and during this process I was using Google Chrome and some Nautilus windows and suddenly something came wrong (compiz or other package was updating...) X server wasn't responding. I had to restart my laptop because upgrading process wasn't going on. Since then Ubuntu doesn't stand up. After grub choise nothing shows (except blinking mouse pointer and purple background). I even can't switch to tty.
Enyone knows solution to that problem? How to repair this installation of Ubuntu. How get access to terminal (to diagnose, to check the system)?