Computer Problems

My desktop was doing fine then all of a sudden it had problems shutting down. Upon trying to restart, a black screen appears giving the option of starting in safe mode, last known configuration etc. I have chosen both modes then the screen goes black. Any idea as to what the problem is. If the harddrive is bad, is there a way that i can retreive lost files? I do own a a laptop now but I no other desktop and there are important files on my defective desktop that i need to retreive.