Wow!! DMailer may have redeemed themselves and I hope this post makes a lot of people happy.
First things first: If you thought you had a secure backup of your data on a WD Passport and you plugged it into a computer that crashed/fried/etc. and planned to copy your lost files to your fixed-up PC from your WD Passport and found yourself (as another blogger said somewhere) like a deer in the headlights as you watched in horror as the WDSync software automatically started syncing your newly blank internal drive (or empty folders on your internal drive) and the Passport, thus "removing" all your "backed up" files from your Passport, you are not alone (and you're not stupid).
DO NOT save ANYTHING to the Passport. The files are not gone yet because they have not been overwritten. They are "deleted" files, which typically could be recovered with some free recovery software from download.com, but alas, they are also encrypted, so just recovering them won't help you. You also have to decrypt them (DMailer uses AES 128-bit encryption). I contacted DMailer and, thankfully, they may have offered a solution. But before I get to that here are some tips about using the WD Passport (which are buried in a DMailer .pdf flier and in an answer on the Western Digital website)...
If you are computer savvy...you should realize that the WDSync software is not backup software and is, in fact, just syncing software. So, if you delete something from your desktop it will delete it from the Passport as well, next time you sync. However, EVEN IF you are computer savvy, you probably wouldn't have guessed in a million years that DMailer would make "autosync" the default setting and that they wouldn't tell you ahead of time or prompt you in some way before it started deleting files. So, if you want to use WDSync to sync your data between your computer and your Passport, before you do anything else, SHUT OFF autosync and always manually sync. If you are not interested in syncing your data and just want to backup your data, skip the WDSync software all together. Don't use it. Just use the Passport like a jump drive and drag and drop your files to it. Your data won't be encrypted or password protected, but download.com offers a number of downloads that will do this for you (specifically for external drives, jump drives, etc.).
If you are not computer savvy...don't use the WD Sync software. Do what I just said. Drag and drop your files to the WD Passport as if it were just a jump drive. This way your data are backed up and you can delete whatever you want from wherever you want without worrying about all your data suddenly vanishing.
Ok, all that said, here's what I did after I was stuck like a deer in the headlights watching my precious files disappear:
(1) Again, DO NOT save anything to the WD Passport after this happens or your files could be gone for good.
(2) Email DMailer (the company that makes WDSync software for Western Digital). Do NOT contact Western Digital, they will just tell you you are screwed. WD's customer support is awful. Go to http://www.dmailer.com
and tell DMailer you just accidentally removed encrypted files from your passport that you need to recover.
(3) This is the response I got:
Thank you for using our product.
We are really sorry for your data loss.
We suggest you to use undelete software and try to recover your source files. Please find below a list of providers for this kind of software: http://www.winundelete.com/?rid=google&kid=wu0406 http://www.recovermyfiles.com/ http://www.ontrack.com/software/
Once you will have recover your WDSync data folder (and files), we will be able to provide you a data recovery tool that will help you to unencrypt these data. For that, you will need your profile's password, options file (.option), database file (.db) and the Dmailer files (.dml).
Please note that this tool is not able to recover file names, and may not recover all your files (this tool doesn't recover emails or favorites too).
(4) Just for kicks, I ran some recovery software and turned up a lot of .dml files, but you shouldn't have to use recovery software if you haven't overwritten your files. Double click on the Passport icon to open the drive. Find the "WD Sync Data" folder. Open the folder for the computer you accidentally synced to (e.g., "office computer"). Open the "Data" folder. There you should find the .option file, the data base file and a folder containing the "deposited" files from the latest sync. In the Sync deposit folder are more folders which should contain the DMailer files (.dml).
(5) Wait for DMailer to get back to you with their data recovery tool. (I haven't gotten mine yet, so can't say how it works.)