Computer Won't Boot: Diagnostic Guide for Windows
Diagnose and fix the most common boot problems on a Windows PC.
This is different from the computer showing no sign of life at all — if that is your case (no lights, no fans, nothing), our guide on the PC won't turn on covers it. This article is for when the machine does turn on (lights, fans, maybe the manufacturer's logo) but Windows never finishes loading.
First, identify exactly when it fails
A boot or hardware problem
It doesn't even reach the BIOS/UEFI.
Windows did load — it's the Explorer that's failing
The system is there, only the graphical part is failing.
A known cause with a specific fix
See the specific section below.
If you see the cursor and it moves (Windows did start)
Press Ctrl + Alt + Del → Task Manager → File → "Run
new task" → type explorer.exe → Enter. If the desktop
appears, you have confirmed the problem is only with Explorer, not
Windows in general — our guide on
File Explorer
covers this specific case.
If the problem started right after updating
From the recovery screen (it opens automatically after 2-3 failed boot attempts, or hold the power button for 10 seconds during startup, repeat 3 times): "Troubleshoot" → "Advanced options" → "Uninstall Updates" — try both the latest quality update and the latest feature update.
Automatic startup repair
From the same recovery screen: "Troubleshoot" → "Advanced options" → "Startup Repair". Windows tries to diagnose and fix the problem automatically.
If automatic repair doesn't work: manual commands
From "Advanced options" → "Command Prompt":
sfc /scannow
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd
These bootrec commands repair the information that
tells the computer where to find Windows on the disk — without
touching your personal files. Run each one in turn and restart to
check whether it boots before moving on to the next.
System restore
If you have a restore point from before the problem started, our guide on restoring the system explains how to do it from this same recovery menu.
Warning: "Reset this PC" (different from restoring) is the last resort — depending on the option you choose, it can delete all your personal files. Exhaust the previous options first.
Frequently asked questions
How is this different from the PC not turning on at all?
They are different stages: 'not turning on' means there is no sign of life at all (lights, fans). This article is for when the machine does turn on but Windows never fully loads.
Can the bootrec commands delete my files?
No, they repair the boot information that indicates where Windows is on the disk, without touching your documents, photos or personal files.
How do I get to the recovery screen if Windows won't boot?
It opens automatically after 2-3 failed normal boot attempts. You can also force it by holding the power button for 10 seconds during startup, repeating this 3 times in a row.