It also said avast had a new version update so i updated it, then it wanted to restart my computer and when i restarted, my steam desktop shortcut was gone again. I just opened my avast a few minutes ago and the virus chest had my steam client in there but I left it alone.
Who knows how many people this happened to and perhaps most of them either didn't think to ask here, or maybe this is the wrong place to ask and they all went to the 'right place'? or maybe I'm less competent than others and they knew how to fix it.