Why is the screen black when I power button it

I found my laptop set in a closet, I got my desktop a year or more ago and haven't been using my laptop at all, so I decided to start using it back again, so I used it properly for about a week after that whenever I was using it the screen froze and it produced a high pitch beep, and now it has gotten to the point that it doesn't starts up. Help if there is anything to be done to save it I would highly appreciate it