Desktop is empty from Dock and icons and everythng

I just installed Ubuntu 20.04.01 L.T.S and after restarting it, Dock and all the desktop icons are disappeared and desktop is empty! but i can reach Dock by clicking on Activities on front left of the screen but it doesn't still bring my desktop things back. when i go to appearance setting, Dock is off. how can i bring everything back to normal...?

Edit: I finally brought back my Dock by searching in Askubuntu.com but Desktop files and icons are still disapeared and i even installed Mate-Tweaks to enable desktop icons but whenever i get to it check enabling desktop icons, it doesn't apply anything and if close and then open it again, there is no sign of any change. its like something in root of system or base of ubuntu is wrong! please help me!