After the reinstall of windows grub disappeared. I think this is a big problem for all of us.
So…
Boot the livecd.
Start a terminal.
and type
sudo -i
grub
find /boot/grub/stage1 // this will print something like (hd0,1) this is the disk that you have to write next
root (hd0,1)
setup (hd0)
quit
then restart your machine and now your old grub menu should be there.
Thanks