About 3 weeks ago, I have accidentally used the "clean" command in diskpart in DOS.. And every thing in the hard drive was removed even the drive letters, it became unallocated space. I used a small part of that space (29.5 GB) to install Win7 and kept the remaining part of the disk unformatted, to avoid any further precious data loss. I used "recover my files" to scan the hard drive, and fortunately it found most of my data, I also used "active file and partition recovery" which gave close results and saved the results of the scan for future use. At the time I didn't have much space so I recovered what I can on another hard drive and kept the drive the same, unformatted in order to recover every thing later and kept using the (C) partition without touching the other partition which appears in "My computer" as (D) but inaccessible and unformatted (Raw). Now I was able to clear some space, and I recovered a great deal of the data. I tried accessing the files but they didn't open. The documents appear to be corrupted, the rar files don't open so as the music mp3 files. Though there space appears accurate and even the music files show album information and stuff, they are useless.. I even rescanned the drive again using "recover my files" which gave similar good results but the files I recover are still inaccessible.. How do I get my files?? And what could have possibly happen different from my first recovery attempt??
"I used a small part of that space (29.5 GB) to install Win7"
That's probably where you went wrong. It will have overwritten the data you were hoping to recover later, thereby damaging the files beyond repair. You should have attempted recovery before writing anything else to that drive.
As long as you have not rewritten all your original data, you do have chances to recover your data back. But, you should also prepare for disappointment since the rewritten data id already gone permanently.
But, now, you can try a drive recovery freeware that can recover your inaccessible data back. Trust me! It has ever successfully restored the data of my friend completely. It is really free and efficient. Try it here: http://www.freeware-fix.blogspot.com/2013/02/data-recov...