Question M.2 Not Booting Into Windows

Jan 15, 2022
A few days ago I switched on my pc and was greeted with a 'could not detect operating system' message. I've never had issues with it before however after reading up on what I could find and trying some bios changes, nothing seemed to work. Under the m.2 section in the bios however, the device did show up under the correct name.
My specs:
Ryzen 3 2300x - 3.5ghz
RX 570 4GB Sapphire Nitro +
16gb ddr4 running at 2933mhz - Kingston Fury Beast
500w 80 plus bronze psu
2tb Seagate Barracuda HDD
And the m.2 ssd that isn't showing up,
500gb Crucial P5

The ssd cost £51 and I only got it a few weeks ago.
Any help appreciated,
Last edited by a moderator:
ASUS Prime B450 M-A ii
So ..
is windows installed on 500GB ssd or on 2TB hdd?
were both drives connected, when you installed windows?

Currently you can't boot into windows. Correct?
Can you boot from windows installation media , execute following and show command output:
(upload to and post link)
list disk
select disk 0
list partition
list volume
Jan 15, 2022
Apologies for not getting back to you sooner and thank you very much for your time.
I thought that it might help to explain my situation in case any other users can benefit from the way in which I fixed the problem.
As for your previous questions, Windows was installed on the 500gb ssd and both drives were connected when I installed Windows.
Correct, I could not boot into Windows and I received a message saying that an operating system could not be found.
I did as you mentioned and tried to boot from Windows installation media - this was successful and the 500gb ssd drive appeared with roughly 100gb of my data on it as it was before the system stopped working.
It said that I could not install Windows on the ssd as it was in MBR format instead of GPT; this is an issue that I've had and fixed before.
Despite this, I have no idea why this occurred as a few days before, the PC was working well and then the apparent change in drive format occurred; if anyone knows why this happened, it would be interesting to hear why, thanks.
I formatted my ssd to change the drive format to GPT (as I had backed it up recently so the data loss wasn't a concern for me) and reinstalled Windows and copied my files back.
I might of interfered with the bios which could of caused the problem, again, if anyone knows if the drive format could of changed as a result of tweaking the bios, I'd appreciate if you could let me know in this thread, thanks again.
My PC has been working fine for the last few days with no issues at all.
I appreciate that simply formatting the drive and changing the format when installing Windows installation media might not be possible for everyone if you have important files that haven't been backed up on the drive (I recommend that you regularly back your drives up,) but if anyone knows of a way of changing the drive format without loosing files or even reinstalling Windows in a better way that I did it then again, I'd appreciate you letting me know in this thread.
Cheers for all the help to those who responded to my initial problem and I'm happy to say that everything's working fine for me.
Lastly, I've just searched for GPT v.s. MBR and apparently MBR can't function properly with more than 2tb of storage (it says no more than 2tb hdd space, not sure if ssd counts then) so there could be a chance that the SATA cable came loose when installing Windows and when it popped back into place, the PC couldn't boot as there would be 2.5tb of storage (meaning that it originally loaded Windows 10 in MBR format ((is this possible??)))
Jan 15, 2022
Okay, cheers I didn't know that.
Still no idea how the format changed then unless the drive initially installed Windows in MBR.