INACCESSIBLE BOOT DEVICE basically means that it can't find a boot device to start up with - this could be due to a hardware issue (failing controller, hard drive etc.), bad setting (BIOS and the like) or corruption (file system).
What you're describing is a permanent error. Its probably occurring at a stage where you can't even invoke Safe Mode.
Follow the start up sequence:
- BIOS
- Does it complete its checks?
- Did you make any changes to the BIOS? If so revert to the previous settings.
- Did you update your BIOS? If so, try to revert back to the previous versions
- Windows
- Does it ever get to anything related to Windows? (I don't think you will but...)
- Try safe mode
- Did you update a driver, setting etc? If so, revert back
One other thing you can try is, make a bootable
- Ubuntu USB, and try booting from that. Mount the drive and see if you see if the files/file structure is intact.
If its none of these, you may need to determine if you have a bad hard drive or do a full reinstall.
You can create a bootable USB drive
https://www.microsoft.com/en-us/software-download/windows10