Why is my Windows 10 unable to use the start menu, nor does the explorer icon in lower toolbar work, help?

[WPCentral Question]

windows 10 unable to use the start menu, nor does the explorer icon in lower toolbar work, help

I have downloaded windows 10, am suddenly unable to use the Start menu, also the internet explorer icon (bottom toolbar) does not work, it flickers on for 1 second only. help please