Recovering overwritten files?

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Recovering overwritten files?

Postby LAV25 » Sun May 17, 2009 10:02 am

Is there any way to recover an overwritten file? I was backing up my spreadsheets and accidentally overwrote the current work with my previous backed up work. My mistake, but is there a way to revert to the previous data? I'm using Windows XP and Open Office 3.0

Thanks for any help you can give.

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Re: Recovering overwritten files?

Postby TheGurkha » Sun May 17, 2009 11:26 am

Once it's over-written by the operating system, to all intents and purposes that file can be considered to be 'gone'. I say 'to all intents and purposes' because technically there is the slimmest of chances, but to discover whether that is the case and to recover the file if it is, can be non-trivial, to say the least.

The recently worked file (let's call it 'new') sits somewhere on the hard disk. Then the backup file (let's call it 'old') is copied to the hard disk. The directory entry for that file is updated by the OS to point to the location of the old file, and the OS marks the space taken up by the new file as empty (available) space, so you can't see your new file anymore.

Typically, if the old file is smaller than the new file, it is dropped right on top of the place where the new file used to be. So the new file is obliterated. But if for some reason the OS has put the old backup file somewhere else on the hard disk and nothing has yet been written into the space that the OS now treats as free and empty (where the new file used to be) then you can sometimes use recovery software to get that file back.

This free tool has had some good recommendations from users of this forum (I've never used it though): ADRC Data Recovery.

Good luck.
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Re: Recovering overwritten files?

Postby Dave » Sun May 17, 2009 3:07 pm

You're painting the walls of your living room. It had green paint, and you decided to paint it red. You didn't just paint over the green paint. You removed it as you were applying the new paint. The new did not cover the old, it replaced it ...or, worse, it blended to give some other ungodly colour. I made some MP3 files from my own LP albums for ease of listening, and to keep the quality of the LPs intact. With all the transfer back and forth of files, some one or two got corrupted. Partway through one piece, another would start then stop, carrying on with the original. How, or why is not important. What is important is that I just shrugged and did it all over again. Now, I just enjoy the music.

An often repeated warning: Backup, backup, backup. I've been saying that for decades, and hope to live long enough to give the same advice decades from now.

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