HP pavilion dv6 blank screen when try login

Hello,

My computer was working just fine yesterday. I switched it off as usual before going to bed. Today i tried to turn it on and it wasn't working. When i push the switch on button everything is in working order. All the lights come on- including the wi-fi and caps lock ones too. The screen turns on, lights up, and the HP logo appears. It then gives me the option for starting windows normally or safe mode it. When i click either of them it gives the same result. The screen darkens- but back light is still on. The courser is visible and i am able to move it around, but that's it. Nothing else happens. At this stage i would have been able to see the login screen were i choose users etc... but my screen is just black, although the back light and courser are visible, and the buttons are responsive.

HELP!