Windows 10: An operating system was not found

Hello Yesterday I turned on my computer , turned it off , tried to boot from an external hard drive with windows 7 installed I was gonna check if it works and turned out it was crashingI was gonna format it using diskpart ,when again turned on my computer with the external hard drive disconnected, it said An operating system was not found.....Im a programmer and we designer but i have never dealt with this in my life...My specsHp compaq 8200 small form factor Intel core i5 2400Amd r5 250 Oem 2gb 128bit ddr38gb ddr3 ram500 gb segate hddWindows 11 pro I have product key but the data on C d

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Programs not working

In post 26 there were steps listed to fix the operating system corruption.
Are you able to follow them?
In post 29 was the suggested dism repair command.

 

' choose an operation system to start"

Hi Bob,

To better assist you, do let us the complete message that you receive.

Sometimes, this could be due to two operating system installed in your computer. Just to make sure this is not the case, I suggest you to try the steps below:

1. Press Windows key + R.

2. Type msconfig and press enter.

3. Click the "boot" tab and check if there are any other operating system listed.

4. In addition, change the timeout time to 3 seconds(default)

Let us know the result, we will be glad to help if you need further assistance.

 

need list of usb bootable Operating Systems

I am looking for a good list of operating systems you can run from a usb or dvd.

If not a list, then folks can just post their top picks.

I want these to run from the usb/dvd without installing on the system or getting in the way of the system that exists on the hard drive.

Thanks in advance.