Deleted GRUB root directory. How do I reinstall grub?

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http://unix.stackexchange.com – I have the following partition structure `/dev/loop0 squashfs /dev/sda1 system reserved ( ntfs ) /dev/sda2 ntfs ( windows partition ) /dev/sda3 ntfs /dev/sda5 ntfs /dev/sda6 ext4` I have Ubuntu installed inside windows. I formatted /dev/sda6 from inside Ubuntu ( using Gparted ). What I totally forgot was /dev/sda6 had Fedora which was the root directory of GRUB. Now how do I recover grub. I have tried chrooting to the ubuntu partition and installing grub. But the boot fails with, " No such device... ". And I cannot install elementaryOS on /dev/sda6 since the installer doesn't go b (HowTos)