Bagaimana Mengunci Layar?

Saya tidak dapat mengaktifkan mode layar kunci di laptop saya dan juga di PC saya. Saya pergi ke pengaturan sistem> layar> kunci
Ctrl+Alt+L :
Tidak ada yang terjadi!
pintasan ada tetapi tidak berfungsi !

sudo apt-get --reinstall install gnome-screensaver :
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 dassault-systemes-draftsight:i386 : Depends: sendmail:i386 but it is not installable
                                     PreDepends: libdirectfb-extra:i386 (>= 1.2.7-2) but it is not going to be installed
                                     PreDepends: libxcb-render-util0:i386 (>= 0.3.6-1) but it is not installable
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

Jawaban yang Diterima:

Ctrl +Alt +L

Pintasan keyboard di atas akan mengunci layar Anda.