I need computer help!

So my PC is being a faggot, and when I turn it on, it won't show me the Start button, the taskbar, any shortcuts, or anything. All it shows me is my cursor and my background. I opened up task manager, and it turns out Windows Explorer isn't running. So I try to get it to run, but it tells me that it can't find it. And if I restart in Safe Mode, I still get the same error. What should I do?