Question Windows PC fails to find boot disk

Aug 30, 2022
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Yesterday I moved the location of my PC. I had disconnected the monitors before shutting down and thought I'd be able to force a shut down by holding the power button. After around 15 seconds the PC turned off. I now come to turn the PC on and get a Reboot and Select proper Boot device... message. I have an MSI motherboard and so I enter the BIOS to try and select the M2 drive that the Windows OS is installed on. No matter which disk I select I always get the same Reboot and Select message. Does anybody have any suggestions as to what I can try? LMK if I need to provide additional info about my system. Thanks!
 
Aug 30, 2022
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Do all of your disks show up in bios?
If it's a newer mobo that has uefi it might have two different boot options for every disk, one for secure boot and one for legacy. (uefi or CSM)

In the worst case you would have to boot from an windows installation media and go into the advanced settings to rewrite an boot block and BCD store
https://www.thewindowsclub.com/rebuild-bcd-windows-10
Yes, all my disks show up in the bios.
The mobo is around 3 years old and so does have the options of legacy and UEFI. I have tried both settings but a boot disk never shows.

I don't mind if I have to reinstall Windows. The trouble is I have two M2 disks that are identical and I'm not sure which one has the original Windows installed on. I don't want to overwrite valuable files.

Would the best thing to do be buy a new M2 disk and start afresh. Once I have the system up and running I could then see which disk has my files on.

Or... anything else I should try?
 
Aug 30, 2022
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I believe I have found USB stick with the Windows Install stuff on it that I used when first building the PC. I have managed to boot up from this. I see the Windows Setup screen > select next > Repair yur computer> Troubleshoot and then went to the DOS prompt. I can see all of the disks in the PC and have verified all my files are ther on the 4 disks that I use for various things.

After that I tried the Startup Repair, but got a message stating Startup Repair couldn't repair your PC.

What should I do from here?

If I reinstall Windows will it overwrite my OS disk. That may not be a problem, but I'd like to understand what the implication will be.
 
Don't do the automatic repair, try the two commands that are in the link I posted, first only the first command bootrec /rebuildbcd ,and if that doesn't work try the second one.
Both of those will not touch your files and will only write on your boot files that are not working anyway so they can't break anything.
 
Aug 30, 2022
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Don't do the automatic repair, try the two commands that are in the link I posted, first only the first command bootrec /rebuildbcd ,and if that doesn't work try the second one.
Both of those will not touch your files and will only write on your boot files that are not working anyway so they can't break anything.
I enetred bootrec /rebuildbcd
Got a message that said Scanning all disks...
It identified Windows installations
[1] G:\Windows
Add installation to boot list? I entered Y
Got a message that said:
The requested system device cannot be found.

I entered the second command:
bcdboot g:\windows /s g:

But god a message: Failure when attempting to copy boot files.

The tutorial link you sent did say:
Do note that you have to boot your computer into Advanced Recovery Mode and then execute this command, else you may see a Failure when attempting to copy boot files error message.

Maybe I haven't booted into Advanced Recovery Mode. Is there a way to tell?
 
thought I'd be able to force a shut down by holding the power button. After around 15 seconds the PC turned off.
Why did you do it this way? Could you not shutdown your pc normally (like you should be doing it)?
You probably got corrupted file system by doing inappropriate shutdown.
I entered the second command:
bcdboot g:\windows /s g:
That most likely is not correct.
You have to find correct bootloader partition drive letter first. Normally bootloader and windows OS are on different partitions.

Execute following and show command output:
(make a screenshot, upload to imgur.com and post link)
diskpart
list disk
select disk 0
list partition
list volume

If you have multiple disks then also
select disk 1
list partition
select disk 2
list partition
...
(for each disk)​
 
Aug 30, 2022
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Why did you do it this way? Could you not shutdown your pc normally (like you should be doing it)?
You probably got corrupted file system by doing inappropriate shutdown.
I had disconnected and moved all my monitors but left the PC running. I guess I should have just turned off the power on the PSU.

You have to find correct bootloader partition drive letter first. Normally bootloader and windows OS are on different partitions.

Execute following and show command output:
(make a screenshot, upload to imgur.com and post link)
diskpartlist diskselect disk 0list partitionlist volume
If you have multiple disks then also
select disk 1list partitionselect disk 2list partition...(for each disk)
Thanks @SkyNetRising. Here's the link for the screenshot: View: https://imgur.com/a/KAzPqvF
 
bootloader is 99MB System partition on Disk 4.

To recreate bootloader execute following:
diskpart
list disk
select disk 4
(select 465GB disk)​
list partition
select partition 2
(select 99MB System partition)​
assign letter=M
exit
bcdboot G:\windows /s M:

In BIOS set first boot device to Windows Boot Manager.

Boot entries without Windows Boot Manager are for legacy boot.
Those will not work (should not work), unless you have a legacy bootloader on any of them.
 
Aug 30, 2022
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I entered as you specified above (I checked and double-checked). When I entered:
bcdboot G:\windows /s M:
I got:
Failure when attempting to copy boot files.
 
Make sure G: indeed is correct windows OS partition drive letter.
Drive letters in recovery environment do not necessary remain the same after reboot.

As mentioned before - you may have caused corrupted file system with inappropriate shutdown.
Run chkdsk on windows OS partition.
chkdsk G: /f
Run bcdboot command again after chkdsk with verbose option ( /v ) and show screenshot.
bcdboot G:\windows /s M: /v
Depending on extent of file system corruption it may be necessary to just do reinstall.
 
Did you verify G: to be the correct OS partition drive letter?
You can check it with
diskpart
list volume

Do not run chkdsk G: from G: drive itself.
Change current drive to a different drive, for example
C:

If that doesn't help, then G: seems to be have become read only.
This can happen, when SSD has exhausted all write cycles and locked itself.
Then you'd have to replace the drive.
 
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Aug 30, 2022
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You can install windows on another drive and diagnose 970 evo with Samsung Magician.
It should confirm, the drive has failed.
Thank you soooo much for your help. I‘ll try what you suggest… and next time I will just plug my monitor back in and not force a shutdown using the PC power button - lesson learned!
 
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Aug 30, 2022
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You can install windows on another drive and diagnose 970 evo with Samsung Magician.
It should confirm, the drive has failed.
I installed windows on another drive, ran Samsung Magician and confirmed the drive has failed (write protected in some way). I have purchased a new 970 evo and would like to clone the original one. Although the original can no longer be written to I can read from it. Do you know how I can do this? I was hoping Magician would do this for me but it will only work if cloning the current OS.
 

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