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LOST.DIR appearing on your Android or PC?

Once with my SD card I had issues with errors and my files just “disappeared”. On connecting the memory card to a PC and checking its contents, I found a folder with the name LOST.DIR (I am assuming this folder means Lost Directory, and therefore should be a directory of lost files, right?).
The content of the folder, however, were files with numbers and no extensions! How on earth would I be able to know how to identify each file and rename them?
There was no way on earth I could identify the file types of each file, not without being a psychic.

But before I begin sharing the solution(s), you may be curious to know…

What is LOST.DIR,and what on earth is it doing on my phone?

There’s a directory called LOST.DIR on sdcards in android phones. From what I’ve gathered, it contains lost/corrupted/orphaned files from the sdcard or recovered during the Android OS startup fsck (File System Check, I believe, not what you were thinking…) . When these files are moved to LOST.DIR, they’re renamed with seemingly random strings of numbers and any file suffixes are stripped. Other OS’s (Mac, Windows, etc.) have similar directories that serve similar purposes. The problem is that many are experiencing an alarming rate of sdcard data corruption, causing the LOST.DIR directory to fill up rather quickly, sometimes reaching multiple GB’s in size. When files are found in LOST.DIR, they’ve actually been removed from their original location.

It’s OK to delete the files, if any, in that directory, but if you delete the directory the mount process will just recreate it on boot-up during the new fsck. If you have files in there, it indicates that something was found to be wrong with your file system on that drive at some point. Deleting the files in LOST.DIR means you’ll never be able to recover those files.

Once files end up in LOST.DIR, it’s painstaking to recover them. Since they no longer have file types/suffixes, you may have to try opening the files in a utility to be able to tell what they are. Or by trial and error try appending different suffixes until you can open the files in an appropriate application.

How do I recover files from the LOST.DIR folder?

There are two ways to solve this problem

The Solution – TRID

TrID is a utility designed to identify file types from their binary signatures. While there are similar utilities with hard coded rules, TriID has no such rules. Instead, it is extensible and can be trained to recognize new formats in a fast and automatic way. TrID uses a database of definitions which describe recurring patterns for supported file types.

Courtesy of developer Mark Pontello, you can retrieve the extensions of files in the lost.dir folder by running this command line tool. All you have to do is download trID from the download links at the end of this post.

There is also a GUI version at the end of this post if you cannot go through the trouble of using command line

To use the command line version, simply type

trid path\filename(s) -ae

Okay not so fast.

Maybe you already understand, but in case you don’t, let’s do this together step by step.

  • I downloaded the trid executable and the trID definitions from Mark’s website. I extracted them too
  • I copied the trid.exe and triddefs.trid files to the root of my C:\ drive (you can copy them both anywhere you wish though)
  • I also copied the lost.dir folder from my phone to the C:\ drive in my computer
  • I fired up command prompt (By cmd.exe at the start menu and pressing ENTER)
  • I navigated to the root of my C:\ drive (by typing cd\ and then pressing ENTER)
  • Then I typed

trid LOST.DIR\* -ae

  • and then hit ENTER
trid command line - recover lost.dir
trID command line

It runs for a while, then outputs a success/failure result.

I check my LOST.DIR folder and bingo! My file types are good!


For the GUI version,

Extract the triddefs_xml.rar into a folder

Run the trID.NET and point the definitions file to the folder you extracted the triddefs_xml

It can only analyse one file at a time, unlike the command line version.

trID GUI. Recover lost.dir
trID GUI. Recover lost.dir

Download links


 Win32  TrID v2.10,
29KB ZIPGUI version
Latest Definitions
 Linux/x86  TrID v2.11,
 TrIDDefs.TRD package,
(5184 file types, 19/11/13)

For full details of the software and to leave a donation, please contact Mark on his website


Another option: Use data recovery software (PAID)

There are tons of data recovery software out there, and I suggest you check out Asosoft Tech’s Android Data Recovery (ADR) tool. Download the trial version here (It’s just 4.3MB)

Lastly, to prevent this from happening in the future, try these few tips

  • Always eject before removal
  • Never remove while files are being modified
  • Never remove from Android device while device is on
  • If you have your device connected to the computer, the SD card will usually automatically mount itself on the computer. Remember to eject it before disconnecting the device.


Experiencing issues? Tweet the author @kcemenike or send a mail to feedback@echo.com.ng
Don’t forget to leave a donation for the original author of the TrID software 🙂

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  1. My computer turned my files into shortcuts later i found the LOST.DIR folder and i already added new files…. do you think i can still get my files back??

  2. Please help! I have downloaded exe and defs but when I go to DOS prompt I get message that triddefs.trd not found! How to overcome this? I tried also using the GUI version, I get the analysis but the file is still not converted.

    Help will be much appreciated, thanks!

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