[ubuntu] Unable to locate grub after dual boot

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http://ubuntuforums.org – Hi, I wanted to dual boot Win7 and Ubuntu 12.04LTS. So, I installed Win7 first. Then I installed Ubuntu 12.04LTS, using the "side by side" option and it went through fine and I got the grub loader asking for which i wanted to boot. Then, there was around 100gb or unallocated space which I made as a partition of windows. After performing that operation (I don't know if that is consequential), I'm unable to boot to any of the operating systems. I get this error message- error: no such parition grub rescue> I can view the Linux filesystem and the Windows Drives and Dat (Hardware)