How can I recover data from a computer with a failed OS?

Despite the steadily improving reliability of modern operating systems, they are still not designed to absolute perfection. Sooner or later, most of them suffer from some technical issues. A system failure may be caused by a hardware malfunction or a software crash and results in the inability of the OS to boot normally. It may constantly reboot and freeze with an error message displayed on the screen or even stop working entirely without any notifications. Though such a problem can usually be solved by reinstalling the OS from scratch, a fresh installation destroys everything stored in the system partition and provokes massive loss of user data from the internal hard drive. That being so, all the critical files need to be copied out from the storage before the newly installed OS overwrites them. Yet, the crashed operating system will prevent any straightforward access to the content of the drive. Fortunately, there may be a couple of ways to settle things down.

To determine the most appropriate course of action, first and foremost, it is important to find out the nature of the problem occurred.


1. Hard drive failure

Unusual noises from the drive, like clicking or grinding, the messages "Invalid System Disk" or "Please Insert Bootable Media", particularly when the machine doesn't detect the drive, are a sign of a disk failure rather than an OS issue. In this case, it's strongly recommended to carefully eject the drive, pack it into an anti-static bag and take it to data recovery specialists for the examination. Further manipulations with the drive without proper training and equipment may lead to its further damage.

2. Defective hardware

Hardware-related problems frequently cause OS failures as the computer becomes unable to function normally. A faulty power supply provokes an immediate shutdown of a system; a bad processor makes it impossible for the computer to process requests or operate in general; a flawed RAM chip may keep the OS from accessing critical data and cause a "Fatal exception error". As a rule, the computer informs about these problems on startup using error codes displayed on the screen or BIOS beep codes. In order to decode them, you may refer to the website of the motherboard’s manufacturer. If you suspect any damage to computer's hardware other the failure of the hard disk drive, you should take the storage medium out of the machine and use another computer to recover the lost files as described in the instruction below.

UFS Explorer and Recovery Explorer are reliable software products that serve for effective data recovery from hard disk drives with any file system of Windows, macOS, Linux or UNIX/BSD, along with a variety of other tasks associated with data loss. Multiple editions are provided to address different storage technologies available on modern devices. The utilities thoroughly inspect the digital medium in a safe read-only mode, extract the lost data and enable its copying to a safe local or network storage.

Hint: For detailed information about the supported file systems and additional storage technologies please refer to the product specifications and the storage technologies page.

If you are performing the procedure using UFS Explorer Standard Recovery, please, complete the following steps:

  1. Prepare another computer that can be used for data recovery. Download and install the software onto it. See to it that the version of the application matches the OS under which it operates.

Hint: If you have any difficulties with the installation of the utility, please refer to the installation manual for UFS Explorer Standard Recovery.

  1. Find a storage capable of locating the recovered files: an internal drive of the host PC, any portable device connected to it or a network folder.

  2. Shut down the defective computer, unscrew its tower and extract the hard disk drive holding the data. Handle the device cautiously and keep it horizontally on a flat surface during the manipulations.

  3. Switch the host computer off and attach the removed hard drive to it using the fastest possible It is desirable to employ a SATA port found on the motherboard, but for convenience you may choose a USB to SATA adapter or a disk enclosure.

Hint: If you don't know how you can plug the drive into the motherboard of the computer or connect it externally using a USB to SATA/IDE adapter, please rely on the provided video tutorials.

  1. Run the host PC and start UFS Explorer Standard Recovery. If necessary, modify the software settings in the respective

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Warning: When you boot the computer, the operating system may prompt formatting or repairing the connected drive. Doing so may cause serious difficulties or even permanent data loss.

  1. Find your hard drive among the connected devices in the left pane and select it for scanning using the corresponding button or option in the storage context menu.

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Note: If your drive is missing in the list of devices, you are likely to have a physically flawed drive/enclosure.

  1. Specify the preferred scan parameters. After that, hit "Start scan" and wait until the operation is finished.

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Hint: More information about configuring the scan can be found in the instruction on scanning a drive with UFS Explorer.

  1. Examine the file system reconstructed by the application: you may sort the files by name, date, type, employ quick or advanced search and preview images, videos, audio files or PDF documents. After that, click "Define selection" and choose the items to be saved by checking them off.

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  2. Pick out a destination folder for the obtained data in the opened dialog.

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Hint: If you are going to save the recovered data to a network storage, please check the provided guide.

3. Software issues

If every piece of the computer system’s hardware is intact, the failure has most likely resulted from a software glitch, like a malware infection, improper system shutdown, conflicts between applications, incorrect system update, bad drivers, wrong settings or boot sequence which has led to the corruption of the partition table, master boot record, critical system files or even the entire file system. You may see the prompts, like "Error loading operating system," "Non-System disk or disk error," "Invalid partition table," "NTLDR is missing," "Your PC ran into a problem and needs to restart," etc. In this situation, data recovery can also be performed on another computer, just like in the previous case. However, if removing the drives from the affected machine is impossible or undesirable, for instance, due to the warranty or lack of expertise, you may use UFS Explorer Backup and Emergency Recovery CD to boot the computer in a safe environment and carry out the procedure without disassembling the device. Having decided on this option, you will need to create a bootable USB device with the downloaded ISO-file and restore files using a live operating system with pre-installed data recovery software as explained in the instructions.

Last update: June 17, 2021

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