Windows 10: I messed up the letter drive registry and can't logged in back to win 10

Hi,,

I'm a user of windows 10 professional.


I recently tried to find back the missing drive letters E: and F: by editing the drive letters from system32 files. I forgot the exact files name, and after restarted from windows 10 it only could go up to the first blue windows logo with black background and continued to a never ending running circle loading.

I've tried to fix it with usb win 10 installation troubleshooter but it said it can't be fixed with that way.


How to fix this problem?

Can i fix / restore the system32 file by removing the SSD and work it via usb with my other windows 10 device?


Thanks

:)

 

User Folder Relocation - drive letter changed / can't log in

Not sure if this is the best thread to post this in.

Here's the scenario.
You use the (amazing) folder relocation tutorial in this forum. The process succeeds and you have a wonderful stress free year in Windows 10. Then your motherboard fails and you replace it with a different brand. Suddenly, when you get booted back to Windows, you can't log in! You quickly realize it's because you set your 2nd hard drive to drive letter "D:", but when Windows reloaded the disk drives because of the hardware change, it assigned "D:" to the DVD drive, and now you are stuck!

Fear not fellow tweakers, I put in the research and have the solution (this may be redundant from another post, tried to search originally but didn't find anything, so my apologies if duplicating).

Quick detail: First, we are going to boot into the recovery console and use the command prompt. In the recovery console, please be aware that it uses a virtual drive "X:" as the OS drive. Your other drive letters will be changed. Then we will identify which drive letter your OS is installed on. Next we will find which drive letter your user profiles are loaded on. Then we will make registry edits to fix the drive letter changes. Finally a reboot and celebratory dance.

Note: You will need an understanding of command line operations and registry editing. If you do not, please find that information first, I will assume you have this knowledge moving forward.
Also, there are no screen shots. I'm sorry, I didn't think I would be posting this while I went through the process, therefore I have no screen shots to share. If anyone has to go through this, it would be great if you could share your experience and provide screenshots if available.

***THIS INVOLVES REGISTRY EDITING. PROCEED AT YOUR OWN RISK. I AM NOT A REGISTRY EXPERT AND CAN NOT TROUBLESHOOT MISSED STEPS OR ERRORS.***

Step 1: Boot into the Recovery Console and select the Command Prompt option.
* If you don't know how, basic tutorial: Interrupt the boot cycle 3 times to activate the recovery consol. As the system boots, when you see the windows logo, simply do a hard reset. After 3 times, when the windows logo appears, it will say it is starting "Automatic Recovery". Once that is done, log in with the local admin account and it will (at least for me) automatically open a command prompt.
* This can also be accomplished a number of other ways including the use of recovery drives, install media, etc.

Step 2: If you are confident on which drive is likely which, you can skip to step 3. If not, you need to determine which drive is which in the registry. To do this you have to use a variety of steps.

1. Find the original OS drive. In the command prompt, type the following command:
   bcdedit | find "osdevice"
   The command will return osdecice partition=*: where "*" will be the current drive letter.
2. Now you need to find the drive that has the user profiles folder assigned, from your folder relocation. There are a few ways to do this, I will list one. Type "regedit" in the command prompt to open the registry editor.
3. In the registry editor, navigate to HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices
4. In this part of the registry you will see all the drive letters assigned to various volumes. From step 2a, you'll know which volume would be your normal "C:" drive. Write down the hex code associated with that drive letter. Next, you need to determine which drive letters represent volumes on physically mounted drives, and which represent removable media. Not getting too technical, basically you just look for all the volumes that have a hex code length equal to that of the OS drive.
   1. For example, if in step 2a you discovered that your OS drive is assigned the letter "W:", then look at the entry with that drive letter assigned. The number of hex entries represents a volume on a physically connected drive. Find all the other drive letters that have an equal number of hex entries. Those are all volumes on physically connected drives.
5. Explore each of those drive letters to find the one with the user profile folder.
6. Do this by typing "dir *:" in the command prompt, where "*" equals the drive letter.
7. Go back to the registry editor (regedit). Find the "DosDrive" key entry with same drive letter as in step 2e. Write down the hex code for that key entry.

Step 3: Before we can make the necessary registry changes, you need to connect to a different registry, called a "Hive".

1. This link has a more expanded explanation of what we are about to do.
2. In the key folder pane (left pane) of the Registry Editor window, highlight the "HKEY_LOCAL_MACHINE" option.
3. Next, click on "File" and chose the option for "Load Hive"
4. You'll have a familiar "open" window, navigate to the os drive found in step 2a.
5. Navigate to the windows\system32\config folder
6. Select the "SYSTEM" file option, and click "OPEN"
7. It will ask for a key name. This is a temporary name and thus doesn't need anything official. Make it easy to remember. I used: "Drive Letter Change". Then click "OK"
8. Now you will see an option under HKEY_LOCAL_MACHINE for "Drive Letter Change" (or whatever you named it in the previous step.
9. Open that new folder and navigate down to
   HKEY_LOCAL_MACHINE\Drive Letter Change\MountedDevices
10. This will look similar to what you found in step 2d, with the notable difference being this is what Windows will look like when not in recovery!

Step 4: Make the registry changes

1. Delete every registry entry that either starts with \\??\ OR has a hex code LONGER than the physical drives (Step 2d).
2. You should be left with \DosDevices\ keys with equal length hex codes.
3. Find the key with the hex code that matches with the OS drive you wrote down in step 2d. Make sure it is assigned the drive letter "C:"
   1. There should be no change in this
4. Find the key with a hex code that matches your user folder drive, you wrote this down in step 2f.
5. Right click that key name and chose the option for "Rename"
6. Change the drive letter to whichever drive letter is needed for your particular setup.
   1. When I did my folder relocation initially, I had set my user folders to be found on the D drive. So on this step I renamed the key from "\DosDevice\E:" to "\DosDevice\D:"
7. Confirm there are no duplicate or conflicting key entries: each drive letter will be used only once.
8. *NOTE* For THIS particular set of keys (MountedDevices), you can safely delete everything thing. Windows will re-initialize these values at boot if it detects drives that are unaccounted for. So, if you delete everything besides the C drive and your user profile drive, that is OK! Windows will reconstruct the missing keys for you. Once you can log in, you can use Device Manager to change drive letters at will. This IS NOT TRUE for all registry items.

Step 5: Close the registry editor

Step 6: Type "exit" at the command prompt

Step 7: Click on the button for "Turn off PC"

Step 8: Count to 10, take a deep breath, and turn the computer back on

Step 9: Log into windows

Step 10: Assuming Step 9 worked, celebrate in your preferred method. If step 9 didn't work, double check you followed my instructions. If not, shut it all down and go to the beach!

 

Reformatting - Wrong Drive Letters?

Ok, do so googling about acronis True Image 11 and disk letters. Its the program I use to save all my info, and I know that people wee having troubles with the drive letters there. It was something about modifying the boot.ini and assigning drives. Anyway, I found this for you:

Change the System/Boot Drive Letter
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows
1. Make a full system backup of the computer and system state.
2. Log on as an Administrator.
3. Start Regedt32.exe.
4. Go to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices
5. Click MountedDevices.
6. On the Security menu, click Permissions.
7. Verify that Administrators have full control. Change this back when you are finished with these steps.
8. Quit Regedt32.exe, and then start Regedit.exe.
9. Locate the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices
10. Find the drive letter you want to change to (new). Look for "\DosDevices\C:".
11. Right-click \DosDevices\C:, and then click Rename.

Note You must use Regedit instead of Regedt32 to rename this registry key.
12. Rename it to an unused drive letter "\DosDevices\Z:".

This frees up drive letter C.
13. Find the drive letter you want changed. Look for "\DosDevices\D:".
14. Right-click \DosDevices\D:, and then click Rename.
15. Rename it to the appropriate (new) drive letter "\DosDevices\C:".
16. Click the value for \DosDevices\Z:, click Rename, and then name it back to "\DosDevices\D:".
17. Quit Regedit, and then start Regedt32.
18. Change the permissions back to the previous setting for Administrators (this should probably be Read Only).
19. Restart the computer.

 

help. USB drive isn't assigned a drive letter.

Any usb flash drive I plug into my computer isn't assigned a drive letter. The physical drive shows in the "safely remove hardware" but it doesnt show up in disk management. I have tried to populate the volume thru the safely remove hardware properties window and it does pop up in the list but it doesn't stay there. This isn't a format or assign a letter problem. It's more complicated then that. Maybe one of the services needed for usb drive management was disabled? Suggestions needed. btw external usb harddrives work fine.