I have a Lenovo g50-80. when I power it on it shows windows system recovery and in the boot options it is set the default to start windows normally and then the windows boot animation is seen and after the animation ends I can see only my cursor with dimmed out brightness on my screen. I have all my important files on my desktop and I don't want to lose them.
Is there a Function key that controls brightness and might have accidentally turned too far down? You might to hold down the Fn key on the left hand side of the spacebar.
If it isn;t that simple, the safest way to start is by removing the hard drive and slaving it to another machine. A caddy which can hold and connect the drive via USB will be quite cheap on e-Bay and while it's finished rescuing the files, you can run a CheckDisk to see if it can find and fix any corrupted sectors.