I agree with JB, it's most likely the hard drive going bad. Since the computer came with Windows 7 it's plenty old enough for the hard drive to develop problems. I would replace the old conventional hard drive with a new SSD.

You can download Windows 10 from here:
https://www.microsoft.com/en-us/software-download/windows10

Click the button that says

Quote:

Download tool now

and save the file. Then run it and it will download the full install and you will have the option to save it as an ISO or create a bootable DVD or flash drive. Hopefully your computer still has the Windows 7 license key decal because you will need the key to activate a fresh install of Windows 10.