Don't get too worked up if your Windows PC won't boot (yet). When your computer fails to boot properly, follow these troubleshooting steps.
Sometimes, unfortunately your computer just fails to start, you pressed the power button as usual but nothing’s happen. Or you can’t enter POST and keep boot looping, or anything. When this stuff happened, don’t panic, there are several things that you can do before you looking for a new laptop or computer to buy.
Are you sure that your machine has sufficient enough power to run it? If the machine doesn’t run at all, fans doesn’t spin, in case of computer there’s no beep from motherboard as well you probably have power issue here. Try to unplug and plug it back first, if that’s doesn’t work try plug it directly into the wall that you know for sure it’s working, also make sure that the power switch is turned on too. If you're using a laptop, make sure that your charger is properly plugged in and connected to the correct port—if it charges via USB-C, only some of the USB ports may provide power. Even if the fans and lights turn on, a failing power supply can frequently cause boot problems. If the troubleshooting steps in this guide are ineffective, it may be time to replace your power supply.
If you’re machine is on, you hear all the fan noises, hard drive noises and the beep for computer user as well but no display output? Ensure that your monitor is plugged in to the socket wall, turned on using the power button. Also make sure that the cabling is right and tight, loose cable is same as not connected. You can also try to plug another monitor or even a TV to your PC and see if it’s outputting something. If not, then you might be needing a new monitor. And, while it may seem trivial, make sure your laptop's brightness is set to high.
When your computer boots, there’s usually a single beep that means everything’s check. But if it failed to boot there’s usually a set tone of beep that will tell you what is wrong. The Manual will tell you what those set of beeps mean or you can just check the manufacture’s web. What if it does not beep? Then you need to buy an internal speaker for it to communicate with you.
What we mean here is only plug necessary devices such as mouse, keyboard and monitor. All external drive, flash drive, head phones. Try to boot it only with essential devices only. In some cases, the problem may not even be with the device itself but with the port on your machine. So check those ports as well.
Often times the machine fail to boot is because there’s a loose part somewhere in your machine. It could be RAM, GPU, or even your storage whether it’s hard disk drive or SSD. Try to remove those items completely and plug them back in and make sure that they plugged all the way in. You could also try booting without certain pieces of hardware, such as the graphics card or one of the RAM sticks, in case they're broken. (And if one RAM stick doesn't work, try the other.)
Certain settings may be causing a problem if your computer turns on and you see the POST screen but you can't boot into Windows itself. An error stating that your computer can't find a bootable operating system, for example, could indicate that your BIOS is set to boot from the wrong drive or that your overclock settings are causing the computer to blue screen immediately. Enter your BIOS when the POST screen appears, usually by pressing Delete, F2, or some other key to enter setup. If you've recently changed any of these settings, try changing them back to default settings.
If BSOD occur at start up, it could be from bad application, driver issue or any hardware problem that causing blue screen of death. By using safe mode, you can enter Windows OS with its very basic features and drivers and try to fix the problem from there. This used to be a simple process in Windows 7, because all you had to do was press F8 while the computer was booting up. It is much more difficult in newer versions of Windows, but usually, if you interrupt the boot process a few times, by pressing the reset button as Windows tries to boot, you will be taken to the Automatic Repair screen, where you can click Advanced Options to enter safe mode.
Alternatively, you can use another PC to create a Windows installation drive and boot from that directly, selecting your language and Repair Your Computer when prompted. Either of these methods should eventually bring you to the Choose an Option screen, from which you can select Troubleshoot > Advanced Options > Startup Settings and reboot the computer. Or if you recently installed new hardware, try uninstalling its drivers from Safe Mode. If you suspect a new application is to blame, remove it as well. BlueScreenView app can help you search through your most recent Blue Screens of Death to find the file that caused the problem, as well as any bug check strings and codes to look up.
If you’re recently update your windows, with or without you realizing it, there’s a chance that that was causing it, sometimes update windows can lead to worse experience, buggy drive and inoperable system. It’s annoying but Windows offer rollback update or downgrade to your previous version of windows.
That’s basically it, of course panicking is happened when your windows suddenly BSOD or can’t booting at all, but do research first, it may be a minor mistake that you can fix it by yourself.