Window 10 isn't responding properly n its not starting on

- laptop's window is recently upgraded from Windows 7 to Windows10 ,but it takes about one start n firstly shows only black blank screen,then when it starts it shuts down immediately after a min r so n again black blank screen remains there,no matter what I do it never starts again until I shut down it manually by button n then start it but again same cycle repeats n also it's not responding properly ,its too slow....please help me..I have to do work n all this mess is wasting my time,thanks