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Windows 10 MBR/partition reset


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#1 Skippywhitefiend

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Posted 26 October 2017 - 04:08 AM

Apologies if this is covered in an existing post, but I cant seem to quite find a fix to a Windows 10 crash that is driving me crazy...

A few weeks ago my desktop PC (home build, fairly old but decent spec e.g. Asus Quad core) crashed after an automatic update - not exactly a BSOD but weird loading and then completely refused to boot. Im running Windows 10 64bit on a dedicated SSD drive, and I have a feeling the Windows update exceeded its capacity. My Whole news was originally Windows 7 64 bit, and I previously deleted the backup/upgrade files to save space on the SSD (sigh!).

I had something similar happen on a newer (and OEM Windows 10) laptop and sequentially worked through these instructions to fix it:
https://neosmart.net/wiki/the-drive-where-windows-is-installed-is-locked/
using a bootable USB version of Windows 10 recovery

On the desktop however, when I get to Step 21 of Fix#5 Set The Correct Partition (which fixed my laptop) I get an error along the lines of cannot find windows installation

I have in desperation tried reinstalling Windows 10 from the recovery USB, but it then claims the disk is GPT (its always been MBR as its an older PC) and wont install.

Any suggestions as to what to try next would be really appreciated! I have used Windows since v3 and still hate it!

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#2 JohnC_21

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Posted 26 October 2017 - 10:19 AM

Please confirm the following.

 

At a command prompt type

 

diskpart

list disk

 

Is there an asterisk under the GPT column?

 

If not and you want to reinstall the OS then do the following commands at the command prompt. This will wipe the disk so all your personal data needs to be backed up first.

 

diskpart

list disk

select disk X      Where X is the number associated with the disk you will be installing Windows to.

clean                  deletes all partitions and sets the drive up for a clean install. Make sure you selected the correct disk in the previous command

convert gpt          do this command Only if you see the asterisk under the GPT column when using the list disk command

exit

exit

 

Continue with the install



#3 Skippywhitefiend

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Posted 26 October 2017 - 04:06 PM

Thanks - there is a * in the GPT column, Disk 0. There is another Disk 1 of 28Gb, Im guessing this is Windows recovery but Windows PE doesnt give me any recovery option.
What should I try next? Ive got important stuff like email and iTunes on a separate drive, but not Windows Users etc

#4 Skippywhitefiend

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Posted 26 October 2017 - 04:13 PM

Bit more info: at point 19 of the guide I referenced earlier I get the system cannot find the file specified, and at 21 is says failure when attempting to copy boot files

#5 JohnC_21

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Posted 26 October 2017 - 04:37 PM

Bit more info: at point 19 of the guide I referenced earlier I get the system cannot find the file specified, and at 21 is says failure when attempting to copy boot files 

I think your Windows install is corrupted and should be reinstalled.

 

If your computer is the old BIOS then it is still possible to boot a GPT disk but it can cause problems. Are you sure the computer is not UEFI? What is the model number of the ASUS computer?

 

When you see disks using diskpart then you are looking at physical disks. Disk 0 and Disk 1 would mean you have two separate disks in the desktop. 28GB seems on the small side unless it's a SSD being used for cache reading and writing.

 

At the command prompt type

 

diskpart

list disk

select disk 0

detail disk                     This will give a detail of the disk manufacturer and serial number. Do the same for disk 1



#6 Skippywhitefiend

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Posted 27 October 2017 - 04:26 AM

I think you’re right about Windows being corrupted, probably by the SSD running out of space during an automatic update.
I’ve got programs on another SSD and data on a HDD, both of which I’ve unplugged so I don’t get confused - but I still managed to forget Disk 1 is the USB I’m running Win PE from! I’ll loose my Windows settings and have to reinstall all the programs if I do a clean install, but I won’t lose data, email etc as they are on the other disk.
Disk 0 is the 60Gb SSD running Windows, configured as: Vol 1 58Gb NTFS Windows, Vol 2 260 Mb hidden FAT32 System and Vol 3 980Mb hidden NTFS WinRE, which I think is standard.
Mobo is an ASUS M4A78T-E (rev 1.02g), which I guess is pretty old! Not sure where the BIOS setting for UEFI might be.
Many thanks for your help, any further advice before I do a clean install?

#7 JohnC_21

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Posted 27 October 2017 - 07:46 AM

Your Welcome,

That motherboard is not UEFI so I'm not sure why it's shown as such under the GPT column of diskpart. Running a GPT disk on a legacy BIOS can present problems as I linked to.

 

I would remove all drives except the one you plan on installing Windows to. Do the diskpart commands except for the GPT command.

Edit: I would substitute the convert mbr command for the convert GPT command.

 

diskpart

list disk

select disk 0     This will be zero because only one disk will be attached.

clean

convert mbr             If it fails then ignore.

exit

exit

 

If you have not created a Windows 10 install DVD or USB lately you can get the latest version using the Media Creation Tool.

 

https://www.microsoft.com/en-us/software-download/windows10

 

In the future I would highly recommend you create complete disk images to a USB external drive using one of the following programs

 

Macrium Reflect Free

Aomei Backupper Standard

Easeus Todo Backup

 

They all allow you to create a bootable CD or USB flash drive. This would allow you to recover your OS should it not boot or of a hard drive failure. On a hard drive failure simply replace the drive, boot the media, and recover the image from the USB external drive. No formatting is necessary. They also allow you to mount the image as a virtual drive letting you pull any file from the image. Aomei and Easeus also allow file/folder backup with Easeus being the easiest to use.


Edited by JohnC_21, 27 October 2017 - 08:18 AM.





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