Unable to lock the administration directory /var/lib/dpkg/ in Ubuntu 12.04

It means, that you are already installing the another software through Ubuntu software center or Synaptic Manager. You can install more than one software at a same time. So, finish for the installation of one software and continue with the other one. But, however if the synaptic manager crashed or you cancel the software installation the process still can be locked. The solution is killing the process and continuing with installing the software. Here’s how you kill the process:

Open the terminal and paste this following command:

sudo fuser -vki /var/lib/dpkg/lock

Press “Y” to kill the process.
Again, use this command to configure and unpack the packages:

sudo dpkg --configure -a