Googled problem.
First option says press Ctrl+Shift+Esc to open Task Manager (easier way I got it by right click on clear Taskbar) then find Windows Explorer (I used search box to find it) in list, right click on it and select Restart. Don't know what happens then as not wanting to try it myself.
Not sure if this will help but if you right click on a clear part of the taskbar you will be able to Task Settings. On there you can scroll down to Notifications and then check that the icons are turned on.