I have a problem with Ubuntu software center. It is "Searching" and "applying changes" for long period of time. I tired to cancel by clicking cross(X) mark. However, it is now stuck at "cancelling". It won't let me download any new application even from terminal i guess.

neal@neal-G50VT:~$ sudo apt-get install gnome-tweak-tool
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
neal@neal-G50VT:~$ sudo dpkg --configure -a
dpkg: error: dpkg status database is locked by another process

There are similar question here, but with no answers:

Software Center stuck for Dropbox

Software Center freezes during “applying changes