Read the statement by Michael Teeuw here.
UNSOLVED Raspberry Pi screen coming black
I am new to raspberry pi but do have an understanding of how things work. I have installed the magic mirror using the quick setup line which you have to enter. Everything went well and was alright until I took out the cable and put it back in to see if it still works. When everything loaded, all I can see is a black screen with nothing coming except for when I right click and I can go in terminal emulator. So I entered the quick setup line again and it came up saying that it is already in my raspberry pi and is in my magic mirror directory. I don’t know what to do? Can someone please help me