ubuntu partition cleared after a windows update

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http://askubuntu.com – Some days ago I'm working on windows and decide update something of the system, then when I reboot I see that the grub disappeared and my Laptop doesn't start, and the screen say grub rescue, ok, I say, I will to reinstall the grub and problem fix, but when I see the partitions with the command -$ sudo fdisk -l I didn't see the ubuntu partition, then go to the partition manager and see a big free space in the place of my ubuntu partition, I dont know how my ubuntu cleared, there are a form to rescue my information or all is losing?! (HowTos)