Given the disk was dropped, the chances that there are just a few bad spots
preventing the partition from being recognized is slim. A mechanical or electronic
failure within the drive itself is unfortunately more likely.
However, if the drive can still seek and read, the following recipe can often be
very fruitful for recovering from bad spots.
1) Obtain a Linux recovery image and boot Linux from either CDROM or USB stick.
For example -
http://www.sysresccd.org/Main_Page
The moment of truth will be if the device is still recognized at least as a raw block device.
This recipe does not care that the drive was loaded with Windows and it will
simply treat it as a raw block device.
2) If the faulty drive still appears as a raw block device, purchase an identical model
drive and connect both it and the faulty drive to the same machine.
3) Run GNU ddrescue to try and recover data from the faulty device to the new device.
This comes on the above cited Linux recovery OS.
See
http://www.gnu.org/s/ddrescue/manual...ue_manual.html
ddrescue uses algorithms to try and recover as much data as it possibly can
by recursively splitting bad blocks and reading them multiple times.
4) Once ddrescue has done its stuff, try seeing if the new cloned disk is readable from Windows.