I have an ASUS-K55V. I had a dual boot with Windows 7 and Ubuntu 12.10.
Recently I upgraded my Ubuntu from 12.10 to 13.04 using the do-release-upgrade command. The update went fine, but after the update when i tried to boot into windows, it gave me an error, and restarted. Then i used a windows installation USB and used the repair commands
bootrec /FixBoot bootrec /FixMbr
When my machine booted this time the grub menu didn't show up, so i used a live Ubuntu USB to recover my Ubuntu. I used the boot-repair tool suggested at Ubuntu Sharing.
Now I got my 13.04 back and i ran the update-grub2 command to recover my Windows, but it does not detect Windows 7 now. I tried using my Windows 7 Installation USB to use the Repair option, but even there it does not detect Windows 7.
Please help me to fix this issue.