upgrade - Problem after upgrading from 11.10 to 12.04

I had installed Ubuntu 11.04 through CD alongside windows.
I got a problem here in upgradation when I upgraded my Ubuntu 11.10 version to 12.04.There were many errors too while installing upgrades..
The package got broken.
After restarting the computer,It should appear Ubuntu 12.04,even here It is appearing ubuntu 11.10 with four dots just moving one by one and does not proceeds further,hangs here!!

Windows is running fine,I restarted computer many times,plugged out the charger...Nothing is working.
How to solve this issue??
I'm not a very frequent user of all this..
Please guide me...