In my Sister's laptop, running Windows 7 Ultimate x86, all of a sudden, while she was working on the computer, the "E drive" went missing which was a partition on the hard disk (I don't remember if it was a logical or primary partition). She tried restarting the system but to no avail. So, I told her to open the "Disk management" tool in Windows 7 to see if the partition is visible in there. I did this because sometimes, in my computer, my expansion drive wouldn't show but it would be visible in the disk management tool and all I had to do was to re-assign it a drive letter. But, in this case, it wasn't visible over there. So, now I told her to download "Mini-Tool Partition manager Home edition" and install it on her laptop. On running it, it wouldn't show the partition either. It would just show "C:", "D", "System Reserved" and unallocated space. However, when I added up the size displayed by C:, D:, System Reserved and Unallocated, it doesn't add up to the actual hard disk size. It means the partition is somewhere there but not visible. Is it possible that the partition would show up correctly if the laptop is booted into the bootable image of Mini-Tool Partition Manager? Any other ideas?