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I had Windows 10 and Ubuntu 16.04 both working with Grub.

After Windows update, I got a screen saying there is no OS installed. I tried Boot-Repair using Boot-Repair-Disk and used recommended repair. Boot-Repair finished and I got a message to restart. After restart, I still get a "No OS" in opening screen.

Boot-Repair summary

Any chance I won't have to reinstall OS?

PC is Dell Inspiron 15 3000 series

marked as duplicate by David Foerster, Eric Carvalho, TheWanderer, Kevin Bowen, Android Dev Nov 29 '16 at 18:05

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  • 3
    Looks like the partition(s) with Ubuntu were removed for some reason. If you're lucky only the partition table entries were removed and the file systems and data are actually still there. See Deleted Partition Recovery and run Boot-Repair again on success. Otherwise you can only try recover your data and reinstall Ubuntu. – David Foerster Nov 17 '16 at 15:34
  • This is MS for you... – Android Dev Nov 29 '16 at 18:05

As to be seen in your boot repair disk summary, there is no Ubuntu operating system on the disk.
So it is not a question whether it is possible to get Ubuntu back without reinstalling, you have to.

There is also no Windows system shown there - whatever happened during the Windows update, it seemed to have wiped everything. I am sorry for being the harbinger of the bad news for you !

Means, unfortunately you will have to reinstall both operating systems completely from scratch, unless you have a backup image. You can try to recover the systems as pointed out by @oldfred.

  • Very old bug in Windows going way back, but now more common with BIOS updates to Windows 10. You can recover missing partition with parted rescue or testdisk. askubuntu.com/questions/654386/… and: askubuntu.com/questions/665445/… If you left Windows fast start up on, make sure you have it off, as grub cannot boot Windows with it on. – oldfred Nov 17 '16 at 15:35
  • @oldfred I agree that fast start should be disabled on dual-boot machines, but GRUB will boot Windows when it's enabled. You should also disable hibernation with powercfg /h off. – heynnema Nov 20 '16 at 0:16

You've probably been hit with the notorious Windows 10 Anniversary Update. This update is known to sometimes wipe out Linux/Ubuntu partitions (why? only Microsoft knows). If you can post a current-window-only screenshot of gparted, I can confirm this case.

Recovery, short of reinstalling Ubuntu, can be difficult, but it may be possible through the use of the testdisk application. Search AskUbuntu for "testdisk" to read what others experience is.

To run testdisk, you need to boot to a Ubuntu Live DVD and install testdisk. Once booted, you open a terminal window and type the following three commands, one at a time. Suggest copy and paste.

  1. sudo apt-get update
  2. sudo apt-get install testdisk
  3. sudo testdisk

For a step-by-step intro to recovery using testdisk, visit http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step.

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