OP:
Do this:
1. Download DataRescue. The download is free.
2. You will need ANOTHER drive to serve as the "scratch drive" for recovery. You cannot get around this.
3. Launch DR and "aim it" at the problem drive.
4. I can't remember if DR has an option to recover from an unintentional re-initialization. If it DOES have that option, try it first. It -might- work at this point.
5. Otherwise, DR should have a "deep scan" option. Try that. Be aware that it could take quite a few hours to run on a large drive. But give it a chance.
6. DR will do its thing, and when done it will present you with a list of "recoverable" files. HOWEVER -- DR (unregistered) will only let you recover ONE file. The purpose of this is to give you a chance to see if it will work for you BEFORE you pay the registration fee.
7. If DR looks like it can do the job, NOW you pay the registration fee, get a code, enter the code, and let DR begin the recovery process.
8. DR will scavenge the problem drive, reassemble and rebuild what files it finds, and save them to the "scratch drive".
IMPORTANT:
Data recovery like this only works if you just did a "quick reinitialization" of the drive. It WILL NOT WORK if you chose to do a "secure erase".
This is because a quick reinitialization only "wipes clean" the directory of the drive, leaving the data "out on the platters" UNtouched. However, a secure erases actually re-writes ones and zeroes to ALL the sectors of the drive. If you've done this, it takes special equipment and techniques to have a chance at recovering the data -- more than you can afford.