Unfortunately, neither stationary hard drives nor removable USB storage media are immune from the fact that at one "perfect" moment they are no longer recognized by the operating system due to a change in one of the standard formats (for example, FAT32 or NTFS) to RAW file system. Why this happens and how to deal with the consequences of such phenomena will be described further. But before you perform certain actions to restore the operability of the media or the data that was originally stored on it, you should dwell a little on understanding the very essence of the RAW format.
RAW file system type: what is it?
So, first a few words about the format itself. What is the RAW file system? Actually, in the usual sense, this is not even a file system, but a format or structure, the presence of which on a hard disk or removable media indicates the absence of a file system that can be determined by the operating system. That is, it is aboutthe fact that the same Windows operating systems do not determine, for example, boot sectors and records, do not see file allocation tables, etc. Because of this, the information stored on such media is not displayed, although the system can determine the full size of the storage device. But Windows cannot get access to it without formatting, and that is why it constantly displays messages that the disk needs to be formatted. And it, in turn, also sometimes cannot be performed, since the same chkdsk command with the RAW file system type is not always able to work.
Reasons for RAW format
As it is already clear, for the RAW format we are talking about damage to the file system, since in most cases devices up to a certain point could be recognized by the operating system, worked without problems, and it was not difficult to access the information stored on them. So why does the RAW file system appear instead of the usual structure? This is usually associated with several factors. for example, very often the appearance of such situations provokes a power outage at the moment when some operations are performed on the hard drive or removable media (formatting, defragmentation, etc.). For flash drives, sudden breakdowns of USB connectors or damage to the microcontrollers of the media themselves are more common. Less common is the impact of virus codes that can destroy organizational data storage structures. Incorrectly installed updates of the operating system itself sometimes make their contribution (some of them may bejust not finalized, or this may be due to errors during the installation of updates).
Check disk from command line
As you can see, there are enough problems. But let's move from theory to practice and see what actions can be taken regarding the RAW file system. How to return NTFS so that the disk or media is detected in the normal mode?

To begin with, despite some restrictions on the use, you can use the command line that starts as an administrator and then execute the command chkdsk X: /f, where X corresponds to the letter of the problem disk, partition or media, and the attribute "/f” is intended to perform automatic error correction. If the system does not initially report that this command is not applicable for the selected disk, you will only need to wait for the check to complete, after which the RAW file system will be converted to NTFS. Unfortunately, this doesn't always work. But after all, somehow the disk needs to be checked and restored? What to do in such a situation?
Chkdsk is invalid for the RAW file system type: how do I check the disk?
In this case, the check can be performed by booting from the installation (recovery) disk or flash drive and calling the command console (Shift + F10). The check command should not be entered immediately, since the first step is to determine the device letter, which may differ from the letter displayed in the environment of the working operating system. First enter the diskpart and list commandsvolume. After completing the second one, it will be possible to find the problematic device, at least in terms of the total volume. After determining the letter, you should exit the console (exit command), and then call it again and check with the above command, but with the input of a specific drive letter or media.
Restoring system components
But suppose that checking and trying to convert the RAW file system did not give the expected effect. What to do in such a situation? If we are talking about a hard drive, most likely, it was important components of the operating system that could have been damaged.

To check them and restore their integrity, use the sfc /scannow command (you can run the command line both in a running OS and when starting from a removable device). After the process is completed, the disk check will need to be performed again.
Format a disk or partition
Now let's see what to do if none of the above options worked and the drive still has a RAW file system. How to return the usual structure? In this case, you can perform formatting, but do not use the standard system tool for this, called through the Explorer context menu, but refer to the disk management section (it will be clear later why). You can access it in the fastest way through the Run console by typing the diskmgmt.msc command. here you need to select the desired partition or disk, and then call the format command via RMB. Note that even in this case, formatting may not always be done.

If the system gives a notification that the process cannot be completed, first the selected partition will have to be deleted, then use the creation of a simple volume for the unallocated area, select the letter in the "Wizard", and only then agree with the formatting by setting the desired file system yourself.
Troubleshooting Removable USB Drives
As for ordinary flash drives, the occurrence of such situations in relation to them is also not excluded. In most cases, the RAW file system on a flash drive appears due to malfunctions in the operation of microcontrollers, incorrectly completed formatting operations or information transfer. It is also not uncommon for a device to be incorrectly removed from the corresponding port when users do not use the actions specifically provided for this.

In principle, you can try to apply the above steps, however, if the main problem is with the controller, you will first need to find out the PID and VID flash drive identifiers through programs like ChipGenius or Flash Drive Information Extractor, then find a recovery program from them (or, simply put, firmware) and reflash the controller with it.
DMDE program
Now a few words about additional methods that can be applied to the RAW file system. How to fix structurecarrier, if the user does not like the previous methods or does not give the expected result? To get started, you can use a small DMDE program. Everything is simple here. First, the disk containing the damaged partition is selected, and then, if it is displayed, its open button is used (the partition can be identified by the icon's strikethrough and file system). If it is not displayed, then a full scan should be specified.

After that, you need to click the show partitions button, make sure that the right one is selected, click the restore button and confirm the actions to restore the boot sector.
TestDisk utility
The RAW file system can also be converted using the TestDisk utility. To an ordinary user, it may seem somewhat unusual, since it works through the DOS console. In a running application, you must first select the Create item, and then the problem disk (namely, the disk, and not the partition). After that, the Analyze and Quick Search buttons are used.

To restore the structure of a partition determined during the scanning process, use the Write button (you can usually leave the partition style suggested by the program).
HDD RAW Copy Tool Application
One more sector-by-sector copy utility can be called no less interesting. It first scans partitions, and after pressing the continue button, it is selected to save the image of the restored partition in IMG format.

Please note that when specifying the path to save the image file, the selected disk or partition must be larger than the size of the file being searched for. After saving the image, it can be used in special information recovery programs that can not only restore lost files and folders, but also reanimate the entire file system (for example, the R-Studio application).
Information recovery
Finally, we assume that the file system has been changed in some way suggested above, but there is no data on the disk or in the partition (for example, as in the case of formatting or sector-by-sector copying). Restoring files is quite easy. It should be noted right away that it is completely impractical to use programs like Recuva for this, since utilities of this level can practically do nothing. In this case, it is better to turn to applications like R. Saver or R-Studio. The first program looks simpler and is designed for the average user. The second utility is more aimed at professionals and can sometimes recover data even after a complete format or critical physical damage to hard drives and removable USB devices, and the results exceed all expectations.

As for the example of saving the image file, it is quite simple to open it in R-Studio and start the data recovery process. It is not recommended to save found objects directly on the media (especially with the replacement of existing content). It is better to choose another disk or logical partition, save everything that is, and only then choose what you want to keep from the found content and what you can delete.
Summary of results
That's all in a nutshell and everything that concerns the recovery of disks, partitions and media, if for some reason a RAW file system appears on them. Naturally, when it comes to specialized programs, it is not necessary to use only the utilities described above. With equal success, you can restore the original format using the Acronis Disk Director package or something similar. But it is still better to recover files and folders on problem partitions or devices using the two applications presented above, since they are the most powerful in their class.