The command linked to uses sudo to get root permissions. This requires the users password, which is what it is asking for (and for sudo to be setup in the right way). You may not have sudo set up that way - I don't, I installed the package rootsh and use the command 'sudo gainroot' to get root permissions. So to run that command, I would run: sudo gainroot apt-get install --reinstall hildon-desktop; killall hildon-desktop exit (the last command logs me out of the root account and back into my user account). I don't know what you do to get root access on your phone though.