missing fedora in grub after installing ubuntu

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http://unix.stackexchange.com – I had fedora 17 in a primary partition. Yesterday I have installed ubuntu in an extended partition. and I cant see fedora in grub, so I trieg update-grub2 but it doesnt recorgonise fedora being present, even the fedora partition is mounted. So I tried to re-install grub from live usb but it didnot work either. How to bring back my fedora? I don't want to re-install fedora in the other partition. (HowTos)