When it comes to data recovery, there are a lot of myths out there. People are recommending Scandisk or some 20 year old DOS utility as the most sophisticated data recovery tools.
When turning to a discussion group for help after a system crash, you often hear: "Just recover from your back-up — you have one, don't you?" Now — that's helpful! Be assured, much of what you hear about data recovery is not true. Read on...
In most cases, this isn't the fact! Whatever happened to your data — whether you accidentally deleted files, a virus has wiped out the boot record, the drive was formatted or fdisk'ed — as long as it wasn't physically overwritten, the data is still there.
The files just aren't accessible the way they should be. For example, if you delete a file, the file's data is not deleted from the drive, but instead, a signature byte is set at the start of the file's name. This signature byte tells the operating systems that this area can be overwritten by other data next. And that's precisely what happens. The next time you write something to the drive, the new data will be written to the so marked area. But this also means that as long as this doesn't happen, the data is still intact and can, therefore, be recovered.
This behavior is also the reason why trying to undelete single deleted files often isn't successful. When you delete a file — and you empty the recycle bin as well — as soon as you notice that you still need the file, the chances are that you have done something in the meantime that has overwritten the data area of the file. Recovering many deleted files is much easier than recovering just one.
Even in cases which seem the most radical — when you, i.e., have formatted your drive from FAT32 to NTFS — and five minutes later realize that you didn't mean to format THIS drive, all of your files are still there. When you format a FAT32 drive, only some structures are destroyed (the boot record, the FAT, the root directory). You still have most files in the subdirectories. And that's all you need! As long as the data is still there, your files can be reconstructed — very often almost entirely.
Yes, it will! Never install or copy anything to the drive you want to recover data from. If you can avoid it, don't even operate the drive anymore. Operate it only one more time after you have attached it to a healthy Windows computer as a second drive, installed the data recovery software on the "good" drive, and want to run the software to scan the "bad" drive.
Writing anything to the drive you have the data loss on, can doom the whole recovery. Installing a seemingly tiny 1 MB program on the drive can mean that you are not only overwriting 1 MB of space on the drive, but you are corrupting 100 MB or more worth of files beyond recovery.
If you lost data due to a physical problem with the drive, i.e., the drive is making strange noises, doesn't spin at all, or is no longer recognized by the BIOS, this might be the case. When a hard drive is physically damaged, no software solution is usually going to bring your data back.
See if you can make an image of the drive. If you can, you can probably recover the data from this image.
The following is true for all data loss scenarios due to logical failures like accidental file deletion, format, fdisk, software or power failure, user error, virus attack, etc.