Hi Alexandra73,
I saw your post regarding the black screen and I will be happy to help. Unfortunately, your computer isn't fine if it is not turning on properly. It could be a software or a hardware problem but if we can't get your Windows to load it will be very difficult to determine the exact problem. Do you notice if the Num or Caps Lock flash at all? If so how many times does it flash? This blink code will indicate the problem.
Try doing a Hard Reset to see if clean restart will get it up and going again. If you do manage to get it going try running the System File Checker tool to check for operating system corruptions. Also, what operating system are you running and product number?
Thank you,