I had windows 8.1, and if i turn it on and of there is nothing But the black screen. The first time i turned the pc on after upgrading, i got passed my login before it blacked out

I downloaded 10 some days ago(the update went smoth. But after i log in the first time all i see is a black screen and my mouse. So i thought iy maybe wan't done downloading. I let it stand still for...