If you are having directory problems with the external drive, the FIRST RULE is "don't try to _write_ anything new to the drive". Doing so may only "corrupt it more".
You have to determine what your problem actually IS.
It could be:
1. Corrupted but repairable file system (directory). It's quite possible that Disk Warrior can rebuild the directory from scratch and restore the drive to good working order. This should be your "first course of action".
2. Corrupted but UNrepairable file system. In this case, even DW may not be able to restore the drive, but you might still get files from it using a drive recovery application like DataRescue III or Stellar Phoenix Data Recovery. (see below for how this works)
3. Bad drive -- could be either a hardware failure with the drive, or the drive is ok and something is wrong with the "controller board" (mounted in the external enclosure).
You should try Disk Warrior first. There is a VERY good chance that if all you have is some "directory damage", that DW may be able to rebuild the directory and get you going again.
If that fails, you are going to need to spend a little money (not "a lot", but some).
For $30, I suggest you get one of these:
http://www.amazon.com/Syba-Connecla...?ie=UTF8&s=electronics&qid=1253062702&sr=1-22
It will serve you well in the future. Money very well spent.
Then, get a "bare drive" to go into it. They're available from many sources, I've had good luck buying Seagate drives from newegg.com.
Hook up the SATA dock to the computer (don't power it on yet). Put the bare drive into it. Now power up. Because the new drive "is bare" (no file system), you'll have to first initialize it using Disk Utility, so go ahead and do this.
When done, you'll have an empty drive waiting on your desktop to recover files to.
Now, hook up the PROBLEM external drive. Does it mount on the desktop at this point (regardless of what Disk Utility may say about it)?
If so, try copying folders/files from the problem drive to the fresh one, one folder at a time, so to speak. You may find that some folders copy OK, but others won't (again, might be directory problems). GET COPIED WHATEVER YOU CAN.
If you can retrieve a good portion of the files from the bad drive, it might be prudent to simply "write off the rest" (assuming there's nothing mission-critical there), re-initializing the problem drive, and "starting over" with it.
If NOTHING else seems to be working, there are programs like Data Rescue III or Stellar Phoenix that can "get to" files on a drive, even one with a completely unreadable directory (or a re-initialized drive). They aren't free, but they often work when all else has failed. If these two apps can't do the job, and you HAVE TO HAVE the data, the next step is usually a data-recovery firm, but they cost A LOT of money.
Get the SATA dock and a bare drive first. You will quickly see the value of having a SECOND "backup" around. The dock makes it easy to swap out drives as you accumulate them. And you can even use CarbonCopyCloner to create a "bootable dupe" of your internal drive using the dock -- and then boot from the dock as well (hold down the "option" key at startup and KEEP HOLDING IT DOWN to see what I mean).
