I updated by Ubuntu with some packages. After that it asked for restart. Then after that, at boot option, Windows 7 option has disappeared. I am no longer able to start Windows 7.
Well hope that you didnt overwrote windows and still there
From your Ubuntu desktop,
open up a terminal and run
To reinstall Grub, with all the options you had, you'll need a linux live CD or pen. Once in a "live session":
1.Open a Terminal
2.Use sudo fdisk -l and locate Ubuntu's partition.
3.Mount said partition in /mnt (replace XY, with the correct letter & number): •sudo mount /dev/sdaXY /mnt
4.Reinstall grub (assuming /dev/sda is your main HDD):
•sudo grub-install --root-directory=/mnt/ /dev/sda