Hi and welcome to the forums.
By "not working" do you mean it does not respond to touch or that it does not show anything (black) or something else? In order to be helpful we need a bit more information from you including:
what device are you using
did any event cause the screen to stop working
what, if any, cures have you tried.
You can't reply directly to this reply so I suggest that you either post another question with more information or register on the forums and post a question in the forum specific to your device.
Roger