Bootable USB containing Windows 10 installer is showing me "An operating system wasn't found" error. Help!

[janefab20]

So I've been trying to install windows 10 to my broken pc, which constantly shows black screen even though we've installed windows 7 and 8 before on it. I was trying to fix it, at first it booted from the usb drive but then it can't find the hard drive, so I followed some command from this forum that was proven working but then after running them at restart my pc won't boot from the usb and instead shows me that error, anyone has an idea how to fix it? would greatly appreciate! Thanks in advance.

edit:
These are the commands I followed
Once in Windows setup, hit shift+F10 to bring up the command line.
>diskpart [enter]
>list disk [enter]
From the list above (assuming you have more than one HD installed, if not it'll be the only one), find the number corresponding to your HD.
>select drive [number] [enter]
>clean all [enter] * see note below
>create partition primary [enter]
>select partition 1 [enter]
>active [enter]
>format fs=ntfs [enter] ** see note
>assign [enter]
>exit [enter]
>exit [enter]

note:
-on "create partition primary" didn't work and told something about the storage is full or something (can't remember anymore)
- but on select partition 1, it worked so I thought I proceed on the process and after this everything after this command works, then on restart of my pc, it can't boot from the usb anymore which contains my windows 10 installer.

 

[Colif]

normally if you installing to win 10 you only need do the clean as the installer itself will do the rest. No need to create the partitions. So you had 2 drives in PC when you did the select disc? The USB and HDD were showing?

I wonder if diskpart formatted the USB as ntfs - that would explain why USB doesn't boot now.

Does hdd show in bios?

On another PC, download the Windows 10 media creation tool and use it to make a win 10 installer on the USB agaiin - see if it boots from it.

 

[janefab20]

normally if you installing to win 10 you only need do the clean as the installer itself will do the rest. No need to create the partitions. So you had 2 drives in PC when you did the select disc? The USB and HDD were showing?

I wonder if diskpart formatted the USB as ntfs - that would explain why USB doesn't boot now.

Does hdd show in bios?

On another PC, download the Windows 10 media creation tool and use it to make a win 10 installer on the USB agaiin - see if it boots from it.

yeah at first, I chose boot menu then selected the name of the usb where the windows 10 installer is, so I proceeded on the installation and windows 10 doesn't recognize my hdd, so I had to resort on finding a solution on this and entered the commands, I have a feeling I formatted the usb itself, I've currently going on the bios set up and it's still there, so I tried putting the usb back and noticed that my bios doesn't recognize the usb anymore as bootable, I will try to make the usb bootable again and see what happens and will update this if ever I encounter the same or new problem, thanks Colif!

 

[Colif]

does hdd show up in the BIOS? How about moving hdd to another PC and see if it shows in it?

if you can boot off USB again, can you show me a photo of the list disk? And that error you got last time if you get it again