Why does my computer say no boot disk has been detected?

Seeing the “no boot disk has been detected” error message when you turn on your computer can be frustrating. This error indicates that your computer is unable to find a bootable disk that contains an operating system. There are several potential causes for this error and a few things you can try to get your computer booting properly again.

Quick Overview of the “No Boot Disk” Error

When you first turn on your computer, it goes through a boot up process that loads the operating system into memory so you can use the computer. Part of this process checks for bootable disks that contain an OS. If no boot disk is found, you will see an error message like:

  • “No boot disk has been detected or the disk has failed”
  • “Boot disk failure”
  • “Non-bootable disk error”
  • “Operating system not found”

Seeing one of these errors means your computer cannot find a bootable disk with an OS installed in order to complete the startup process. Let’s look at some potential reasons why this happens.

Potential Causes of the “No Boot Disk” Error

There are a few common causes for the “no boot disk detected” error:

Damaged or disconnected hard drive

If your hard drive containing the OS has become damaged or disconnected, your computer will not be able to boot from it. Possible damage includes:

  • Hard drive failures from old age, overheating, power surges, etc.
  • Accidental damage to the hard drive from drops or shocks.
  • Corrupted system files from a virus or other software fault.
  • Loose or unplugged SATA/IDE cable connecting the hard drive.

If the hard drive itself has failed or has a major corruption issue, it is unlikely your computer will be able to boot at all. You may hear odd clicking or beeping noises from a damaged hard drive when attempting to boot.

Boot order not set properly

The boot order tells the computer which disk to check first for an OS. If your boot order gets changed incorrectly, your computer may be checking disks without an OS before the actual disk where Windows/Linux is installed.

For example, if a USB flash drive is set as the first boot device, the computer will check there first and not find an OS. Meanwhile, your actual hard drive with the OS installed is set further down the list.

OS system files corrupted

An operating system requires many critical system files to function properly. If certain files like the Master Boot Record become corrupted or deleted, the OS may no longer be bootable.

Potential sources of critical file corruption include:

  • Faulty system updates
  • Virus infections
  • Improperly shutting down the computer
  • Unclean installations of a second OS (dual-booting)

Damaged BIOS/UEFI boot loader

When you first turn on a computer, the BIOS or UEFI firmware initializes the hardware components and looks for an operating system loader. If this low-level software has become damaged from a power surge or faulty update, it may no longer be able to start the boot process.

Fixing the “No Boot Disk” Error

If you encounter the “no boot disk detected” message, there are a few basic troubleshooting steps to try:

Check connections and power cables

Make sure all hard drives and SSDs inside your computer are properly connected via their SATA or power cables. It’s amazing how often a cable can come loose enough to cause boot issues. Also verify the power supply cables are not damaged and all components are receiving power.

Inspect your hard drive

If you suspect your primary hard drive is damaged, try removing it and connecting it to another computer (using something like an external hard drive enclosure). See if you can access files on the drive. Listen for any odd clicking or spinning sounds which can indicate physical failure.

Boot to a recovery disk

All Windows and Linux versions come with bootable recovery media that contain utilities for diagnosing and automatically repairing boot issues. You can boot from the OS install disc or make a recovery flash drive.

Once booted to the recovery environment, run the repair/recovery tool. For example, the Automatic Repair option in Windows setup will diagnose and fix common boot issues without losing your installed programs and files.

Reinstall or replace the hard drive

If no physical damage is found, reinstalling the OS fresh may overwrite any corrupted system files causing boot issues. Just be sure to backup any personal files first.

As a last resort, the hard drive may need replacement if it is old or faulty. Installing a new blank hard drive will also involve reinstalling your operating system from scratch.

Preventing “No Boot Disk” Errors

You can help avoid boot disk errors by:

  • Always safely shutting down your computer
  • Keeping good backups of important files
  • Using a UPS to protect against power outages
  • Scanning for and removing malware
  • Keeping software and drivers updated
  • Handling laptops carefully to prevent hard drive damage

Catching and correcting minor system file corruptions early using disk utilities can also often fix small boot issues before they become major.

Recovering Data from a Non-Booting Drive

If your primary hard drive will not boot properly, how do you recover important files from it before reformatting or replacing it? There are a couple options:

Connect the drive externally to another system

By removing the hard drive and connecting it as an external drive to another working computer, you can often directly access the files on it. This could be done using something like a USB hard drive dock, enclosure, or adapter cable.

As long as the drive is not catastrophically damaged, you should be able to open folders and copy files from it to backup elsewhere. If the computer detects issues with the drive itself, you may get warnings about needing to repair/format the disk before using it.

Use recovery software

If the drive has more serious corruption or formatting issues, data recovery software may be able to copy off what files it can interpret. Professional utilities like SpinRite can rebuild directory structures and recover data even from severely damaged drives.

Data recovery software works best when problems are limited to boot sectors or file system tables rather than physical read/write heads, seized motors, or scratched platters.

Getting Help Diagnosing “No Boot Disk” Errors

If you have tried the basic troubleshooting steps for a “no boot disk” error but your computer still does not start properly, it’s time to seek additional help:

  • Consult phone or in-person tech support – Major computer manufacturers often have phone and chat support you can use for troubleshooting boot errors on their branded devices.
  • Take your PC to a local repair shop – Local computer repair technicians have the skills and tools to diagnose boot issues and recommend cost-effective solutions.
  • Send your drive to a data recovery pro – For difficult data recovery cases, a dedicated data recovery service can attempt extracting files from non-functional drives.

Booting issues like the “no boot disk detected” error are often repairable. With the right troubleshooting steps, you can get your PC booting properly again.

Cause Fixes
Damaged hard drive Replace hard drive, attempt data recovery
Disconnected hard drive Reconnect SATA/power cables
Incorrect boot order Change BIOS settings to boot from correct hard drive
Corrupted system files Start repair from recovery disk, reinstall OS
Failed BIOS/UEFI Update BIOS/firmware or replace motherboard

This table summarizes common root causes for the “no boot disk detected” error along with potential solutions for each case.

Frequently Asked Questions

Why do I get a “no boot disk” error even though the hard drive is connected?

Some potential reasons you may get the error when the hard drive is plugged in include:

  • Hard drive is connected but sustained physical damage
  • Boot order is incorrect and computer tries to boot from wrong drive
  • Hard drive’s system partition with boot files is corrupted
  • Drive is not getting power even though SATA is connected

Can I boot the computer from a USB or DVD if my hard drive isn’t detected?

Yes, most computers support booting from external media like flash drives or DVDs so you can access your files and reinstall the OS.

You will need to adjust the one-time boot menu or change the boot order in BIOS to boot from the external device instead of the hard drive.

How can I tell if my hard drive is physically damaged?

Clues your hard drive may have physical damage:

  • Loud clicking, grinding or buzzing sounds from the drive
  • Errors detected when connecting the drive to another computer
  • Cracks, dents or damage to the drive casing
  • Burnt smell coming from the drive
  • Drive makes noise but does not spin up

Severe physical damage typically requires a data recovery service or replacement of the drive.

Can I recover data if I can’t boot from the hard drive?

Yes, there are a couple options to recover data from a drive that won’t boot:

  • Connect the drive externally to another working computer and copy files from it
  • Use data recovery software to access files and folders on the damaged drive
  • Send to a professional data recovery company for extraction of files

The less hardware damage the better chances of recovering data. Be sure to backup any recovered files.


The “no boot disk detected” error at startup often indicates an underlying problem with your system hard drive or boot configuration. Typical fixes include repairing your current OS using recovery tools, replacing the damaged hard drive, or reinstalling your operating system from scratch.

Ruling out physical damage first, then attempting repairs from an external boot disk can help identify the core issue. Getting your computer to successfully boot again should be possible using most consumer troubleshooting methods.

In rare cases where the hard drive has failed catastrophically or data recovery is critical, enlisting professional help ensures the best outcome. With patience and using available support resources, you can get past the dreaded “no boot disk detected” boot error in most cases.