Stuck in "Diagnostic Startup" after choosing it in msconfig, sytem is not booting anymore

If you could get into Windows then you could do an in-place upgrade repair but this can’t be done within safe mode.

If you can access Windows now then there’s several options:

If you can’t use restore health it may indicate the recovery drive has corrupt files, you could try & point restorehealth to a windows installation media:

Option 2:

Insert your installation CD or USB. From Admin Command, run:

1. DISM /Online /Cleanup-Image /StartComponentCleanup
2. DISM /Online /Cleanup-Image /CheckHealth

NOTE: If it says: repairable, go to step 3, if not go to OPTION 2

3. Dism /Online /Cleanup-Image /RestoreHealth /Source:wim:D:\sources\install.wim:1 /limitaccess

The install.wim file will be in the Sources folder of a mounted Windows 10 ISO from Microsoft Tech Bench http://www.tenforums.com/tutorials/3579-iso-img... (use ISO from OPTION ONE at link) file.

4. sfc /scannow

NOTE: may have to run multiple times until you get the message: Windows Resources did not find any integrity violation.

OPTION 2:

Open the drive where your installation media is and run Setup.exe. Follow the instruction to perform update which actually does a repair

This is to fix a corrupt user profile so I don’t know whether it’ll work in your case or if you can run it if you can’t access Windows but worth a try:

Right Click on the Windows 10 Start button and click on Run.

Run Command in Windows 10

2. Type regedit into the search box and press Enter.

Regedit Command Window in Windows 10

3. Now, navigate to the following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList.

Registry Hkey Local Machine Software

Once you follow the file path and reach ProfileList, you will see folders starting with S-1-5. Each of these folders represents a user profile or a user account created on your computer.

4. Click on each S-1-5 folder and identify the folder that is related to the user account that you are trying to fix.

You will be able to clearly identify the user account that each of these folders is related to by taking a look at the ProfileImagePath entry that you will see on the right side of your Window.

User Account Profile Path in Windows 10

5. Once you have identified the right folder, Double Click on the entry “State” to launch a pop-up window (See image below) and change the value to 0.

Edit Dword "State"

6. Next, Double Click on the entry “RefCount” to launch a popup window (See image below) and change the value to 0.

Note: If you do not have RefCount, then you can create a new file by right clicking anywhere on the blank space in the right pane – Click New > DWORD (32 bit) > type RefCount > click on Enter.

Create New Dword File

7. Close regedit and restart your computer. You should now be able to log into your account.

https://www.techbout.com/fix-corrupt-user-profi...