OS-Prober won't find Windows 7

Question

I was using a cracked Windows7 copy that came pre-installed with my assembled PC. Installed Ubuntu 16.04 on one of the two harddisks while Windows 7 was intact on the other.

I havent been able to boot into windows 7 whatsoever. Can't even use the boot-order to boot as the windows 7 shows some DHCP, PX0E stuff.

Here's the relevant sudo fdisk -l results.

Disk /dev/sda: 149.1 GiB, 160041885696 bytes, 312581808 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: gpt
Disk identifier: 83FA66EA-A765-45FC-B7F6-86DC2264BFA7

Device         Start       End   Sectors   Size Type
/dev/sda1       2048   1050623   1048576   512M EFI System
/dev/sda2    1050624 304295935 303245312 144.6G Linux filesystem
/dev/sda3  304295936 312580095   8284160     4G Linux swap


Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x9b74d7a5

Device     Boot      Start        End    Sectors  Size Id Type
/dev/sdb1             2048     206847     204800  100M  7 HPFS/NTFS/exFAT
/dev/sdb2           206848  293799935  293593088  140G  7 HPFS/NTFS/exFAT
/dev/sdb3        293799936 1910671453 1616871518  771G  7 HPFS/NTFS/exFAT
/dev/sdb4       1910673406 1953519111   42845706 20.4G  f W95 Ext'd (LBA)
/dev/sdb5  *    1910673408 1953519111   42845704 20.4G ef EFI (FAT-12/16/32)

Partition 4 does not start on physical sector boundary.

Answer 1

Ugghh I feel your pain. I think you may need to reinstall grub. Try creating a live disk/usb first. Make sure you can boot it. Then follow these instructions. http://howtoubuntu.org/how-to-repair-restore-reinstall-grub-2-with-a-ubuntu-live-cd