Mario recently replaced his hard drive with a Samsung Solid State Drive. Then he upgraded to Windows 10. The computer went to sleep. And now it won't come back on. He managed to get a boot menu by pressing F12. But nothing else. Leo says that means the screen is still good. But it could also mean that the hard drive died. Even though it's new, they can die out quickly. If your computer is old enough, it could be the CMOS battery has died and needs replacing. Check the date/time in the setup. If it thinks it's 1969, then that's what happened. See if you can see the drives in your BIOS setup. From the chatroom - change the drive connection from AH to AHCI. Reset the ESCD system configuration data, unplug all USB devices, and reboot. See what happens.