Why does my computer turn on but show a black screen?

Because you never see the manufacturer logo or BIOS/UEFI screen, Windows has not yet reached the point where Safe Mode, drivers, or Startup Repair can help. This is therefore a pre-boot display, firmware, power, or hardware problem. Disconnect peripherals, remove power, hold the power button for 20 seconds, then reconnect power and one monitor. On a desktop with a discrete graphics card, verify the cable is connected to the GPU output and try another output; if the processor supports integrated graphics, test the motherboard output after powering down. Reseat the graphics card and memory only if you are comfortable and warranty terms permit it. Listen for beep codes and check diagnostic LEDs. Try Windows+Ctrl+Shift+B once, but no BIOS image makes it unlikely to help. If the minimal configuration remains blank, use the manufacturer’s hardware diagnostics or arrange service; a Windows reinstall would not address this symptom.