Ubuntu – How to unprotect a file which is owned by root

By default, the root account is accessed by sudo.

For a complete discussion in the topic, and information for how to set a root password, see: RootSudo - Community Ubuntu Documentation

With that said, it is extremely unlikely you need to set a root password, I advise you use

sudo -i

Or for graphical applications, use gksu

gksu nautilus 

Assuming you are the owner of the operating system in question then you can do something relatively simple. Also assuming the current file is owned by root and group of root then in a terminal you can:

sudo chown your_user:root /path/to/file

You may now edit this file using your normal GUI login.

Once you're done, remember to set it back

sudo chown root:root /path/to/file

To find out more about changing ownership of files see:

man chown

Opening a terminal can be as simple as opening the application bar (name?) and typing "terminal". Using sudo you will be asked for your password to grant you elevated privileges for making the change. See:

man sudo