HDD allocated after upgrading to Windos 7

[Juancho19]

Hi there, I recently installed Win 7 on my PC. I used to have XP. I have a HDD IDE, the one is running Win7. I also I have a 2TB sata drive that I use as a slave. Before I installed Win 7. The Sata drive was working fine until I upgraded to Win 7. Now my HDD does no show on MY Computer screen. I have all my important information in that Hard Drive. When I go to the disk manager, it shows the drive, but it says unallocated. What can I do, how can I retrieve all the information. I have in the HDD. I do not want to lose all my data. Thanks!!

[regaining space - attachment deleted by admin]

[Transfusion]

As a rule of thumb, I always unplug all unnecessary drives while installing an Operating System to avoid messing up.
1) Before we make any unnecessary modifications to the drive, could you slave that drive to another computer to see if your data is retrievable?
2) Did you accidentally format the partition?
3) You could try http://www.cgsecurity.org/wiki/Testdisk to recover partitions from a corrupted partition table.

[Juancho19]

I did not format the drive.

[Transfusion]

Okay, then have you tried the other options I listed above?