Corrupted Files

Computer files can get damaged in several different ways: by a power interruption, by virus or badly written software, by bad RAM or by physical damage to the hard disk.


The laptop starts as usual but when Windows starts to load it goes to black screen with either “UNMOUNTABLE_BOOT_VOLUME”, “hal.dll is missing or corrupted” or “windows\system32\config\system” (or similar) is missing or corrupted. These error messages indicate a corrupted filesystem or a failing hard disk, about 40 / 60 chance.


The easiest way to diagnose and possibly fix corrupted filesystem is to start the computer from a bootable CD, then scan the hard disk for errors. If the scan completes successfully, the registry can be restored by hand and the computer can be scanned for viruses.

The best way to do that is first to make an UBCD4WIN CD on another computer and start your PC from it. To make the UBCD4WIN you will need a working computer with high-speed Internet and CD burner, and a standard Windows XP SP2 installation disk, “Home” or “Pro”. It is possible to use XP installation disk without a service pack or with SP1, but it will have to be slipstreamed to SP2 before building UBCD4WIN (see for details). This is by far the best bootable CD for Windows users, as it will let you use your computer as usual. It comes with hundreds of free programs and utilities that can help you fix almost all software problems.

After starting your computer from UBCD4WIN, go to “Start” button -> Command Prompt and type chkdsk /r /f c: (in the black window that opens). This is the native Windows command for scanning and fixing your “C” drive. Depending on the size of your “C” drive and the number of files you have, this may take from about 30 min. to over 2 hours and if there are errors on the HD – even longer.

If chkdsk shows a lot of errors, especially in “Step 1” or “Step 2”, you will have to replace the hard disk. You still should let chkdsk finish fixing the disk, so you are able to eventually copy your files to the new disk later on.

If the hard disk is very damaged, chkdsk either won’t start scanning at all or won’t be able to finish scanning it. It will get stuck and stop working. In this case the chances of you being able to copy your files to the new HD are slim. If your files are very valuable, you may consider sending the HD to a data recovery service, however the prices for that start at about $500.

If chkdsk was able to finish scanning the HD showing many errors, shut down the computer, replace the hard disk (if it’s easy to do so) and reinstall/restore Windows, or send the computer for service if it’s still under warranty. Then mount the old HD in an external USB box and try to copy your files. If you have chosen “Make my account private” when you were choosing your password, you won’t be able to open the old “My Documents” folder. Here are some instructions on how to fix that.

If chkdsk finished without any errors, or just 2-3 errors, you can assume that the hard disk is working properly. The file corruption may have been caused by freezing, restarting by itself, improper shutdown of the computer (pulling the cord), viruses or sometimes by bad RAM. If you suspect that there may be any viruses on your computer, use one or two of the antivirus programs that come with UBDC4WIN. To do that you will need Internet connection.

If the error message that prevented the computer from starting was “UNMOUNTABLE_BOOT_VOLUME” or “hal.dll is missing or corrupted”, you can try restarting the computer as normal (not from the CD). If it still doesn’t start (both in normal and safe mode) you will have to reinstall/restore Windows, but first backup your files.

If the error message that prevented the computer from starting was “windows\system32\config\system (or similar) is missing or corrupted”, now you should restore the registry files by hand. To do that (still from UBDC4WIN) navigate to “C: -> Windows -> System32 -> config” and rename software to software.1 and system to system.1. Open another window and navigate to “C: -> System Volume Information -> _restore{any-numbers-and letters}”. There you will see a few folders named “PR” + some number. Sort them by date (right-click on empty space and choose “Arrange Icons By -> Modified”) and open one that’s about a week old. Inside you will see one folder and many files. Open the folder.

Now copy the files named _REGISTRY_MACHINE_SYSTEM and _REGISTRY_MACHINE_SOFTWARE to the other open folder (windows\system32\config). Then rename them to only SYSTEM and SOFTWARE (no extensions).


* The Windows System Restore is useful in only two occasions: the one described above and if a driver or Windows update doesn’t install properly and the computer wouldn’t start in normal mode but still starts in safe mode.

40 thoughts on “Corrupted Files”

  1. Dear sir,
    i have acer aspire es 15 series laptop with original windows 10 with recovery when i installed antivirus if restart it wont boot it go direct to automatic recover and gives an option for restart or advance boot option pls help us

  2. I have an Asus wind 10 laptop that corrupts 95% of the files that are dragged and dropped onto external hard drives. It’s not a problem with the hardrives becuase they work seamlessly with other computers. (I use macs at work)

    This happened when before I upgraded to a samsung SSD and for 4 months things were normal then it started happening again, then I got a better anti virus, removed unneeded stuff and defragmented my disk and it was normal for about 2 weeks. Now its because and disk cleanup and defragmenting and reformatting hard drives has not work. Nothing is being picked up on scans (Malwarebytes)
    Sorry its so long, thought as more detail be better. Please help!

  3. I was resetting my Acer with windows 10 and it couldn’t get past 2 percent and eventually it went black. Whenever I try to turn it on it just goes to a screen saying “Acer” for about 10 seconds then it goes black for about 20 seconds and does that over and over

  4. Sir \WINDOWS\SYSTEM32\CONFIG\SYSTEM file gets corrupted can I fix it via pendrive as CD-ROM is not functioning ….plz reply me sir on my E-mail ID shergill1…

  5. sir my frequently used applications stoped working so i uninstalled and reinstall it back but ever since all the files in the programs files of the application got corrupted.

  6. I have Lenove G70 and when I run some aplications it shows me errors and I dont know what I have to do?
    How I can Recover my System32 folder when there are some files/folders missing? Please Help me

    1. I have Lenovo G70 and when I run some aplications it shows me errors and I dont know what I have to do?
      How I can Recover my System32 folder when there are some files/folders missing? Please Help me

  7. Sir I have hcl laptop and it going continuously On and Off .Sir I install win 7 loader on it and then it was happen and it was also not going to boot.

  8. sir my name is raviraj sir in my laptop i seeing some problems that problems is photos folder photos are not opening and photo name are there in green colour. (windows photo viewer can’t open this picture because you dont have the correct permissions to access file location .)what is the problems sir.

  9. See what my laptop shows me,files corrupted,press r for repair.start it from d original cd rom. What should i do

  10. One question. Why was the ability to paste a spreadsheet into the word button removed when the editor was updated about a year ago. This has caused me so much extra work as the data, now copied in from the same spreadsheet, has lost all formatting . Having tables is not the same unless the data is copied and pasted cell by cell. One of the websites I administer uses an earlier version and still has this ability. Linking the spreadsheet is not an option as data is passed to me for inclusion by many people.
    Will you ever consider adding this “wonderful” button again?

  11. I opened cmd prompt for doing c and c++ and I put
    c:\>cd tcp
    disk full not enough swap space.

    wat should I do

  12. I have a samsung NP300V5A-S09AU and it won’t listen to the system restore or repair it just says PC CORRUPTED. NEED HELP PLEASE! 😥

  13. My laptop is showing me error 15 what should I do?? These are things its showing me
    Windows without loader
    Windows wit Slic loader (use alternative method)
    Windows with Slic loader (use low memeory)
    Windows with slic loader (full debug output)

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