Missing Taskbar, icons and black screen

On my laptop, I was surfing the internet when it shut down. I turned it on again but it had a black screen with no task bar, missing icons and no start button. However, an anti virus program is running and sometimes the windows explorer (with all files) shows up?

Can you find a way how to fix this problem?
(Also before this happened, the anti virus program had some virus notifications. Is this the root of the problem?)