I was installing an item using package manager when it froze. I used Alt + F2 to close it.

Afterwards, whenever I try to install anything via apt-get, the terminal reads:

E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists/

How do I unlock /var/lib/apt/lists/?

merged by jokerdino Feb 26 '13 at 3:03

This question was merged with Unable to lock the administration directory (/var/lib/dpkg/) is another process using it? because it is an exact duplicate of that question.