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INACCESSIBLE_BOOT_DEVICE blue screen? How to save your files

November 6, 2026

Your PC starts, shows the logo, then drops to a blue screen with the stop code INACCESSIBLE_BOOT_DEVICE, and it does the same on every restart. It is an alarming message, but it does not mean your files have gone. It means Windows lost contact with the drive it was starting from, and that can be caused by anything from a changed BIOS setting to a failing SSD. The important thing is to work out which before you run a repair that could make matters worse.

What the error means

Early in start-up, Windows loads the driver it needs to talk to your storage, then switches over to reading the system drive through it. INACCESSIBLE_BOOT_DEVICE (stop code 0x0000007B) appears when that hand-over fails. Windows cannot reach the boot volume, so it stops rather than carry on. The message tells you where start-up failed, not why, so there are several possible causes.

Common causes

  • A changed storage setting. A BIOS update, a flat CMOS battery or a settings reset can switch the SATA mode between AHCI and RAID. On newer laptops the same thing can happen with Intel RST or VMD settings. Windows then does not have the right driver active.
  • A Windows update or driver problem. An update that stopped halfway, or a new storage driver, can leave the system unable to load correctly.
  • A drive moved to a new computer. Windows installed on one machine does not always start on different hardware.
  • File system corruption. A power cut or forced shutdown can damage the structures Windows needs to mount the volume.
  • A failing drive. Bad areas on a hard drive, or a dying SSD, can stop the system files being read at all.

The first three leave your data untouched. The last two are where careless repairs do the damage.

Safe checks to do first

  1. Think about what changed. A BIOS update, a new drive, a repair or an interrupted Windows update is your best clue.
  2. Unplug everything you do not need. Remove USB drives, docks and memory cards, then restart once.
  3. Check the drive is listed in the BIOS or UEFI. If it is missing, or shows the wrong name or size, treat it as a hardware fault and stop here.
  4. Check the storage mode. If the setting has moved, put it back to its previous value. Change only this one setting and make a note of what it was. Be careful on a PC that uses a RAID array, as the wrong change there can cause further problems.
  5. Listen to the drive. Clicking, buzzing or repeated spinning up and down all point to physical failure. Switch off straight away.

Find your BitLocker key before going further

Many Windows 10 and Windows 11 laptops are encrypted without their owners realising. If Windows asks for a recovery key at any point, or if you plan to move the drive to another computer, you will need that key. Look in your Microsoft account on another device, or ask your IT department if it is a work machine. Without it the data cannot be read, by you or by anyone else, so find it before you change anything else.

Repairs that can cost you your files

If the drive is healthy and the mode is right, the Windows Recovery Environment offers Startup Repair and the option to uninstall the latest update. Both are reasonable to try when the drive shows no sign of failure. Be much more careful with these:

  • Reset this PC. Even with “Keep my files” selected, it rewrites a large part of the drive, and “Remove everything” is far worse. Do not use it unless your files are safely backed up.
  • Reinstalling Windows. A clean install overwrites data, and installers can make it easy to delete the wrong partition.
  • Running chkdsk /r on a suspect drive. It forces the drive to read every sector, which can finish off a failing disk. On a corrupted volume, it can also change or discard damaged file records, which can leave files harder to recover.
  • Repeated restarts. Every attempt to boot puts more work on a drive that may already be struggling.

Getting your files off before you fix Windows

If there is no sign of physical failure, the safest order is to copy your files first and repair Windows second. You can start the PC from a Windows or Linux USB stick and copy documents to an external drive. Another option is to connect the drive to a second computer with a suitable adapter, as long as you have the BitLocker key if one is needed. Copy the most important folders first, in case the drive gives up partway through.

Stop if copying freezes, the drive disappears or files come back with errors. Those are signs of a hardware problem, and carrying on can turn a recoverable drive into one that is not. Some laptops also have storage soldered to the board, so the drive cannot be removed. In that case, leave it to a specialist.

When to get professional help

If the drive is missing from the BIOS, is making noises, or holds work or photos with no backup, it is time to stop. A recovery engineer will make a copy of the drive with equipment built for unstable media, then work on that copy, leaving the original untouched. Our Windows data recovery page explains more, and you can also read about laptop data recovery and SSD data recovery.

Need your files back?

Call Data Retrieval on 020 7064 4996. We offer a free assessment with no obligation, so you will know where you stand before any work is done.