I just installed Ubuntu 16.04 LTS with an USB, and now when I turn on the computer(Lenovo ideapad Z460), I have options for Ubuntu and Windows 10. But when I choose Windows 10, it just comes back to the choice between Ubuntu and Windows. What should I do to be able to re-use Windows 10 system again ?

I updated GRUB several times but in vain, I tried to run the updated grub too. My windows system still does not boot.

I tried boot-repair, but it didn't work.

My boot-repair pastebin

Maybe the Windows system is damaged because I have chosen the 'Ubuntu and Windows co-existing" option?

ouyang@ouyang-Ideapad-Z460:~$ sudo fdisk -l [sudo] ouyang 的密码:

Disk /dev/sda: 465,8 GiB, 500107862016 bytes, 976773168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xc3ffc3ff

设备       启动     Start    末尾    扇区   Size Id 类型
/dev/sda1  *           63 443002096 443002034 211,2G  7 HPFS/NTFS/exFAT
/dev/sda2       443002878 976768064 533765187 254,5G  f W95 扩展 (LBA)
/dev/sda5       675854613 976768064 300913452 143,5G  7 HPFS/NTFS/exFAT
/dev/sda6       443002880 671811583 228808704 109,1G 83 Linux
/dev/sda7       671813632 675854335   4040704   1,9G 82 Linux 交换 / Solaris

Partition table entries are not in disk order.

  • Boot Ubuntu and update-grub – Elder Geek Feb 7 '17 at 16:03
  • 2
    Possible duplicate of How do you run update-grub? – Elder Geek Feb 7 '17 at 16:03
  • Hi, thanks for your answer. I still can't do it. I updated grub several times but seems in vain, maybe I made some mistake when installing Ubuntu ? How can I know ? – Ouyang Feb 7 '17 at 16:28
  • boot-repair can be useful in situations such as this - see here. My usual approach would be to look at the output of sudo fdisk -l to examine the partitions but I'm so old school that I remember when dual-booting meant turning on 2 computers. ;-) – Elder Geek Feb 7 '17 at 16:39
  • Could you look at this for me ? – Ouyang Feb 7 '17 at 17:16

You destroyed Windows boot, by installing grub to the NTFS partition.Windows NTFS partition has to have more Windows boot code and start & size of NTFS partition embedded in the NTFS BS - boot sector or PBR - partition boot sector. While grub can be installed to a PBR, it almost never should be, and it never should be installed to NTFS. We filed a bug report 5 years ago and it supposed was fixed, but grub still lets you install it.

Fortunately NTFS keeps a backup. If only overwritten once, you should be able to restore from backup. Some Windows tools may do that, but you can use testdisk from Linux. Testdisk may say that BS is valid as grub in PBR/BS can be correct, but it is never actually correct in NTFS. Just restore the backup if shown as valid.

PBR - partition boot sector NTFS must be Windows [HowTo] Repair the bootsector of a Windows partition - YannBuntu



GRUB is not letting me switch to Windows 8. Dual boot process. Ubuntu 15.04

As described, testdisk has an option to "Recover NTFS boot sector from its backup" If Backup BS isn't available, choose RebuildBS, otherwise Windows repairs will not work, but then you must use Windows repair disk and run chkdsk.

Instructions - see section on NTFS partition boot sector recovery


You want to get to this screen:


select [Advanced] instead of [Analyse] and select [BackupBS]


I dont see UEFI partition in the partition list. (like 200MB EFI).

If you deleted it - it means you were also messing with BIOS setup UEFII/legacy - it is a difficult situation. You should start new windows installation - and you can try to recover windows. If not possible, try to backup all valuable from windows and reinstall it. You - most probably - will loose your linux installation.

And my personal impression - you may really do not need windows...

@oldfred - yes, I have spotted Grub at NTFS now, this is problem number 1, I am adding +1 to your answer

  • Thank you, I still miss things like "Spotify" on Windows though. Windows IS less quiet than LINUX... – Ouyang Feb 7 '17 at 18:01
  • BTW, do you have any idea about how to backup valuable documents from Windows ? I can not open it. – Ouyang Feb 7 '17 at 18:08
  • @Ouyang spotify.com/cz/download/linux . Quiet - this I dont know. I would mount the windows partitions into /mnt/disk1 and /mnt/disk2 and I think they should be accessible. The command is like mount /dev/sda1 /mnt/yourdir. Under root. Sorry if you are experienced.. – jaromrax Feb 7 '17 at 18:23
  • I'm kinda desperated because I'm so un-experienced... what can I do ? – Ouyang Feb 7 '17 at 18:43
  • do with what? keep getting experiences - no pain no gain. Now you already know something – jaromrax Feb 8 '17 at 8:51

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