|If the disk structure is corrupt and unreadable then I suggest that you NOT try the freezer trick.|
You need to use a utility to reconstruct the file system on the drive.
Testdisk or Easeus partition recovery.
Get them at the links below. Be sure to read all the instructions BEFORE attempting to use. Easeus MAY be shareware now, not sure. Test disk is absolutely free.
If you have bought another eternal drive I suggest you clone the corrupted disk to the new one and attempt to recover the partition using that drive.
Go to Disk Management and see if the external drive you are having trouble with shows there. If so, the file system may show as RAW. That is a good sign and you should be able to fix the partition. If that is the case the most likely cause is improperly removing the drive. You should always use the safely remove icon the the tray by the clock.
What Phil and trvlr are telling you is to maintain a MINIMUM of TWO copies of any files you wish to keep. More if they are irreplaceable. I back up to external drives and for things like family photos, burn them to DVDR.