Re: grub has stopped booting windows 10

[Darac Marjal <mailinglist@darac.org.uk>]

On Sun, Jan 15, 2017 at 06:36:36PM -0600, Charles E. Blair wrote:
>   I have been running version 7.11 of Debian for several
> years on a desktop with a dual boot of windows and linux
> via grub.  I upgraded to windows 10 roughly 8 months ago,
> and the system continued to work.
>
>   On January 9, I noticed that the grub menu no longer
> displayed a windows option, instead displaying linux
> options twice.  This problem may have occurred earlier
> without my noticing it.  The file /boot/grub/grub.cfg
> was modified on January 4.  I do not know enough to
> interpret it.
>
>   I give below an abridged output from fdisk -l.  I
> suspect the windows 10 system is supposed to be on
> /dev/sda1 or /dev/sda2, but I don't understand what's
> going on.
>
> Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
> 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
>
>   Device Boot      Start         End      Blocks   Id  System
> /dev/sda1   *        2048     3074047     1536000   27  Hidden NTFS WinRE
> /dev/sda2         3074048   491355297   244140625    7  HPFS/NTFS/exFAT
> /dev/sda3      1924173824  1953523711    14674944   17  Hidden HPFS/NTFS
> /dev/sda4       491356158  1924173823   716408833    5  Extended
> Partition 4 does not start on physical sector boundary.
> /dev/sda5       491356160  1890959359   699801600   83  Linux
> /dev/sda6      1890961408  1924173823    16606208   82  Linux swap / Solaris
>
> Partition table entries are not in disk order

I think that, with Windows 10, /dev/sda1 would be the boot partition and 
/dev/sda2 would be the system partition.

What is the output of (as root) "os-prober"?

Can you manually start Windows 10 by the following?

* At the grub menu, press 'c' for a command line.
* Enter: set root=(hd0,msdos1)
* Enter: chainloader +1


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