So I updated Ubuntu to 14.04 a few days ago and I just noticed Windows 10 went missing from the grub menu options. I tried multiple variations of update-grub and tried using boot-repair, too, but nothing fixed it. Here's the pastebin from boot-repair.I'm at a loss as to what to try next. Any help?EDIT: After reading a few suggestions elsewhere, I tried editing /etc/grub.b/40_common, and here are its current contents:#!/bin/shexec tail -n +3 $0# This file provides an easy way to add custom menu entries.  Simply     type the# menu entries you want to add after this comment.  Be careful not to     change# the 'exec tail' line above.menuentry Windows 10 {    set root='(hd0,msdos1)'    chainloader +1}menuentry Windows 102 {    set root='(hd0,msdos2)'    chainloader +1}But booting from either Windows 10x option doesn't work.Option 1 (set root='(hd0,msdos1)') displays this error (imgur .com/AbymY1r.jpg), which stays onscreen for about half a minute or until I ctrl+alt+del out of it (which restarts the computer and goes back to grub).Option 2, on the other hand, gives off this error:BOOTMGR is missingPress Ctrl+Alt+Del do restartI tried using the repair options through the Windows 10 installation disk, and assorted commands within it (e.g. bootrec /RebuildBcd, bootrec /FixMbr and bootrec /FixBoot), but all that did was screw up grub again, and I ended up not being able to boot to neither Ubuntu nor Windows. I made grub come back by using the Ubuntu Live CD, now I'm back to the same problem, except for these new Windows 10 entries I manually added to grub.This is the output for fsbkl -f:NAME   FSTYPE LABEL           MOUNTPOINTsda                           sda1 ntfs   System Reserved sda2 ntfs                   sda3                        sda5 swap                   [SWAP]sda6 ext4                   /sr0EDIT 2: SOLVED!So, I managed to solve it by following Christian_Sosa's answer at MS support, basically run chkdsk on the windows drives and then try startup repair. In my case, chkdsk did the trick.
Windows 10 missing from grub after Ubuntu update
ubuntu;windows;dual boot;grub
So, I managed to solve it by following Christian_Sosa's answer at MS support, basically run chkdsk on the windows drives and then try startup repair. In my case, chkdsk did the trick.Boot Repair mode from a Windows 10 install disk.Launch the command promptType the following commands:diskpartThis will launch the disk partition utility, we will want to know the volume disk letter for where our OS is located.list volumeIt should list your HDD as well as their drive letter. Remember the drive letter that is in a HDD that most resembles the storage capacity. It may or may not say boot for file description.In my case, I had to repeat this process both for C: and D: drives, though both had very different sizes.exitIn order to run the next command we will need to exit the disk partition utility.chkdsk /f X:replace X for your boot os drive letter that we confirmed earlier.Reboot the system back into the Recovery disc.Choose Startup Repair and let it run.In my case, Startup repair never actually ran, but I tried anyway. It seems chkdsk alone did the trick. And for the record, the correct grub menuentry in my case wasmenuentry Windows 10 {  set root='(hd0,msdos1)'  chainloader +1}Thanks for the answers and comments.