I've been installing ubuntu restricted extras via the software center. Everything was going well at first, but then the installation process froze on 'applying changes' stage. I've had this in the past already, and usually just hitting the 'cancel' button helped, but not this time.

Obviously, the install process has placed a lock, and I couldn't issue any apt-get commands. then i've tried doing what was suggested here Fixing Could not get lock /var/lib/dpkg/lock :

sudo fuser -cuk /var/lib/dpkg/lock; sudo rm -f /var/lib/dpkg/lock

but it seemed to me that it has only killed my X server. Okay, i've just pressed the power button on my PC, and restarted, hoping that the lock was finally off and i could reinstall the stuff.

No dice. when I open the software center, I still have one operation in process, a weird one: " Searching | Cancelling ". The 'cancel' button is either inactive, or it just does nothing. So I've become desperate and decided to write here.

How do I fix the problem? Can't install anything on a fresh ubuntu 12.04 :)

Thanks in advance