Did W10 squash my dual-boot? :'(

[williamstome]

I previously had W7 and Ubuntu 14.04 dualbooting, running fine for the longest time.
The other day, I upgraded W7 to W10. Foolish me!
Now, I can no longer boot into Linux! I've used boot-repair, but to no avail.
When (in boot repair) I do an fdisk -l, I get what's seen at the end of this post.
/dev/sda4 looks like it must be my Linux partition, right? It looks like the only thing big enough, but its "extended" label bodes ill.
Furthermore, GParted shows sda4 as unallocated!!!
How can I get my 'buntu back?
Or did W10 squash it?
:/
-Tom

================================================== ===


Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 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
Disk identifier: 0x4e9d6223

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT
/dev/sda2 206848 1047654399 523723776 7 HPFS/NTFS/exFAT
/dev/sda3 1047654400 1048575999 460800 27 Hidden NTFS WinRE
/dev/sda4 1048578046 1953523711 452472833 5 Extended
/dev/sda5 1936814080 1953523711 8354816 82 Linux swap / Solaris

Disk /dev/sdb: 4089 MB, 4089446400 bytes
61 heads, 60 sectors/track, 2182 cylinders, total 7987200 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
Disk identifier: 0xcc38a5b1

Device Boot Start End Blocks Id System
/dev/sdb1 * 736 7987199 3993232 b W95 FAT32

[light_yagami2]

Press ESC when booting up and see if it shows your partition. You should be able to boot from it. After that, I'd backup any files, format that partition and reinstall ubuntu to get grub back.

[oldfred]

You have been bitten by a bug in Windows, since many versions ago. Does not seem like a priority for them to fix.

http://askubuntu.com/questions/654386/windows-10-upgrade-lead-into-grub-rescue/655080#655080
Windows 7 to Windows 10 MBR partition missing
http://ubuntuforums.org/showthread.php?t=2288988
http://ubuntuforums.org/showthread.php?t=2290190
http://ubuntuforums.org/showthread.php?t=2292545
Use parted rescue to restore missing partition details in post #22
http://ubuntuforums.org/showthread.php?t=1775331
http://www.gnu.org/software/parted/manual/html_node/rescue.html
http://gparted.sourceforge.net/faq.php/#faq-22
Parted rescue seems easier than testdisk
http://askubuntu.com/questions/665445/upgraded-to-windows-10-on-dual-boot-and-cant-boot-to-ubuntu-partition/665462

[yancek]

As I understand this problem from reading a number of posts from people who have upgraded to windows 10, the upgrade modifies the partition table and doesn't include the Linux partition. If you look at the start and end points for sd4 and sda5 (swap) you will see a very large protion of unused space which is where I expect your Ubuntu was, about 460GB partition. I don't use windows so never had to deal with this. You might do a search here at the forums while you are waiting for a response.

[williamstome]

I followed the instructions above, and successfully got the machine to recognize Linux. However, I multiple errors prevented booting into it. I ended up flushing it and reinstalling Linux on the relevant partition, as everything important was backed up. :/