Are Corrupted Files Recoverable

[Vinnie Frevert]

Iused Recuva and EASEUS Data Recovery Wizard to see if there's any difference in the files they recover. Both software were able to recover files that I want however most of the files where no longer usable. For example, for images, when you view them it's just black, for .doc files, MS Word can no longer open open them. They appear to be corrupted. This happens on both Recuva and EASEUS.

What happened was that those files were fragmented, and once they were deleted, the cluster chain was removed, so when the programs "recovered" them, what they did was to look at the starting location (which is still present) and the size of the file (which is also still present) and simply copied that many clusters in a row from the start.

This works fine if the files are stored in a single, contiguous block (i.e., defragmented), but if they were fragmented, then their blocks are spread out around the disk and the program has absolutely no way to know where/which ones to use; that's why most of the corrupted recovered files will have at least one cluster's worth of correct data, but then contain whatever happened to be in the subsequent clusters that used to belong to other files.

If the files are plain-text, then you could search the drive for unused clusters (which is a nightmare with a giant, nearly empty disk) and manually stitch the file back together (I did this a few times many years ago). But with binary files, this is effectively impossible. In fact, even with plain-text files, it is difficult at best if the file had been getting edited and saved after changes numerous times because it then becomes difficult to identify the clusters that contain blocks of the last version of the file.

The above explanation is how some data-recovery programs work. It is generally more reliable because it looks at real files that existed more recently. However (not surprisingly perhaps), it can miss out on some files. That is why other programs like PhotoRec use a different approach. Instead of looking at a deleted file's information (filename, size, timestamp, starting cluster) in directory entry and then copying the clusters from the disk, they search the whole disk for lost files.

Most file types have a signature (usually at the start of the file, in the header) which contains a sequence of bytes that identify the file as a certain type. Because of this, programs that open a file can determine if the file is teh correct type and other programs can verify the type of a file.

What some data-recovery programs do is to search the disk and check each cluster to see if they contain the signature of various different file types. If a cluster contains a signature, then it copies that cluster (and more depending on various factors) to a file.

It doesn't help after losing files, but for future reference, the best way to increase the chances of a successful recovery is to keep the disk defragmented (have the system automatically defragment when it idles).

So, yes, fragmentation can be an issue when recovering data but is not by definition. For example, it depends highly on the file system you are recovering data from. It also depends on how the data was lost.

For example, assume a formatted volume and we'll compare FAT based FS vs. NTFS: Yes, in the FAT based FS (FAT32, exFAT) fragmented files are an issue because the file allocation tables were wiped during the format. On NTFS most MFT entries will survive and as long we have those fragmented file recovery is no issue at all as we have the complete runlists for the files.

Example 2: a RAW volume. This can be caused by major file system corruption but also by something as simple as a corrupted boot sector BIOS parameter block. If the latter on both FAT32, exFAT and NTFS volume you should be able to achieve a close to 100% perfect recovery, fragmented files or not. However the reason that popular tools like Recuva and Easeus often fail in these situations are that they're not that good in working out a valid virtual file system.

Then one remark about software that scans for file signatures, or 'carvers'. It is true that for many files it is not possible to detect a file end so you potentially end up with huge files. However there's plenty of files that you can detect file ends for + there a number of rules of thumb you could apply here too.

There are tools specifically designed to puzzle together fragmented files even with absence of any valid file system structures. However, they often work only for very specific file types, such as JPEG, or MP4 or XLS. The reason for this being they need specialized 'knowledge' about the actual file structure to reconstruct valid files.

I am a photographer and videographer. I was shooting a small gig at a local bar on my Canon EOS 60D. I needed another SD card that could handle RAW video; one of my good friends said he uses microSD cards a good bit for his video work. I went and bought an Extreme Plus 32GB Red/Gold U3 microSDHC with an SD adapter. I formatted the card, took some photos and video. Everything was fine. I shot the gig.

When I went to export the RAW files to my MacBook Pro, most of my video files and almost 60 of the still shots reported an error message as being corrupt/damaged/unreadable. All files are PERFECT when viewed from the DSLR. When viewed on the computer, damaged still-images show horizontal banding and video files freeze-frame (the audio continues to play fine). I have never dealt with this type of issue, so I have no clue where to start. Is this possibly an issue with the card or my card reader? Could this be resolved with a simple free file recovery program? Any advice is welcome.

since the files show up and work fine on the camera i would suggest connecting the camera with the cable to the computer with the card and see if you can transfer and see the files on the computer. So in that case you can use the camera as a card reader to check if the files are still corrupted or not

There is possibility an issue with the card or card reader, so you should exclude the problem first. Connect SD card with another well card reader to check whether the file is ok to open. If the problem still exits, then a recovery software is needed. In fact, most of free file recovery program is bundled with spam and useless advertisements.

RePicvid free photo recovery could restore corrupted photos, but it pays to retrieve videos and audio files. You may try the free version to scan and preview corrupted/damaged/unreadable videos. Here is the tutorial about how to recover deleted photos/videos from SD card. Hope it can help you.

1. Try Another Adapter/Card Reader or USB Port

The card reader is also a delicate device. It can get damaged, so it is essential to check if the SD card is working in another card reader; also, try another USB port if the port is not working correctly.

There are a few different Revit files in the project, and this employee is able to access all the other ones with no problem. Also, all the other team members are able to load the file and sync with no problem.

I would suggest detach the central and then reupload central file again to 360. Sometimes corruption may linger in one of the local temp folder and we may not be able to know which one had that issue.

Yeah, I've thought of that, However I'm trying not to disrupt all the other people using this file. When you say lingering files in a local temp folder, do you mean a specific one? I'd like to just delete all the temp files and see if that works, but I don't know of any more besides the CollaborationCache and PacCache.

So I figured it out. I hadn't deleted the user's "Windows\Temp" files as well as their "\AppData\Local\Temp" files. I deleted all of those, ran Disk Cleanup, and re-deleted the "CollaborationCache" and "PacCache" files. It worked!

This worked for me as well. What a grandiose error message when in fact the file/data isn't corrupted, merely the local machine is affected. You'd think Autodesk would know the difference and build in some type of "auto-purge" to these program-breaking directories. This is considering the comment is 2 years old...maybe be Revit 2024 they'll get it right.

I saved an Affinity Photo file I was working on last night, and upon trying to open it today, I was told it was corrupted. The file is saved to a USB, and I don't have any backups. I saw it mentioned earlier that Affinity Designer files saved to external hard drives can corrupt. I generally save directly to a USB, however I've never had a file corrupt before.

To save time I am currently using an automated AI to reply to some posts on this forum. If any of "my" posts are wrong or appear to be total b*ll*cks they are the ones generated by the AI. If correct they were probably mine. I apologise for any mistakes made by my AI - I'm sure it will improve with time.

Hey, could someone check if something can be done with this two files please? It has a lot of working hours on it! I'm with fingers crossed and heart in he mouth over here. Thank you in advance!

(2nd file in next entry)

I see you may be using networked/dropbox storage, try downloading again, from the forum, directly to your C drive and try opening it from there. Non-local drives are known to corrupt Affinity documents

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