Question : Problem: Scrambled files on portable hard drive after some sort of failure. Can they be restored?

a buddy of mine had most of his critical files backed up to a Western Digital portable USB 160 gig drive.  One morning after successfully using the drive the previous night, he noticed that it was showing up in My Computer, but wasn't accessible any longer.  It showed no capacity and no files.  I had him bring it over here and after using OnTrack's Easy Recovery program, I was able to successfully retrieve most of the files off the drive.  

Or so I thought.

After transferring all of the files to another portable USB drive, we noticed that the files and the names seem to be separated from one another.  For example:  a large Photoshop file that may have originally named: "LAYOUT2.PSD" will now be named "_AYOUT2.PSD" and have a file size of 0 bytes.  Looking through the other files in the directory, there are a bunch of .tmp files that were not on the original drive. If I take one of the larger files, like a file named "~ps1C2F.tmp" and just change the extension to .psd so that the file name is now "~ps1C2F.psd", Windows XP now recognizes that file as a Photoshop file ... and in fact, the Photoshop "preview" image will appear in My Computer.  However, when I attempt to open that renamed file in Photoshop, it will not open:  I get an error stating that "the file is not compatible with this version of Photoshop."  It's almost as if each file was split into two parts .... with one part, the .tmp file containing the bulk of the file, and the other part with the "_" in the name being the name portion of the file.

What's going on here?  Is there some sort of utility that can restore these files?  What happened on that original Western Digital Drive to cause this?  My buddy's got some major hours into some of those Photoshop files, so it would be good to be able to find some way to retrieve them!

Answer : Problem: Scrambled files on portable hard drive after some sort of failure. Can they be restored?

i would first take the disk out of the enclosure, and try to run the recovery soft. Getdataback and Stellar are among the best :  
http://www.runtime.org/                                    GetDataBack
http://www.stellarinfo.com/                                    Stellar
if this does not help, try these guys :  http://www.handyrecovery.com/      
also, with usb devices, this can come in handy :  http://safelyremove.com/?pid=1      

btw - after recovery, run a disk test on that drive, to be sure about it's status :  http://www.tacktech.com/display.cfm?ttid=287