Lock Desktop Icon Missing?

Ive searched the web even this forum and thus far i havent found anything that has been able to fix my problem.
My Kali linux is working well its updating and everythng is working fine.
The problem i am facing is that somewhere whilst i was messing around with the different desktop enviroments i messed up something, as now i have no option to lock the dektop only logout and power off.

ive tried the option to lock screen in the settings menu even the varied shortcut keys to lock the desktop but nothing is working for me.

I even made VMS of it so that i didnt do anymore more damage.

i really dont want to rebuild as im new to Kali though loving it and i have things working just the way i want it to for now.

Is there a command or something i can run / do to restore the option to lock the desktop and put the icon back in the menu ?.

im running a gnome desktop

Sham