Have an Acer Aspire where the Hard Drive Failed. Need help.

I have a Acer Aspire where the hard drive completely failed.  It had Windows 8 on it but took advantage of the free upgrade to Windows 10.

I also have a 500 gig hard drive that I reformatted and have been trying to get the computer to install Windows 10.  Doesn't want to work.  I have a Windows 7 installation disk with key code.  I always thought that Windows 7 was a stable program and that I would be happy with that system.  I am thinking that in the Firmaware my Acer Aspire does have stored that the system had Windows 10 activated on it.  I have had no luck in getting either system installed.

I was able to get into the Acer BIOS and set the BIOS settings to Legacy.  I can't set it to boot into the CD for the Boot Order so I have not been able to get the opportunity to install Windows 7.  I would sure appreciate any and all help. I formatted the one drive to NTFS and made that the default.

Thanks again.  I am stumped.

If Windows 10 ran on the computer you should be able to install it again. The license is digital and on Microsoft Servers. If the computer came pre-installed with Windows 8 then the key is embedded in firmware. Can you give a detailed explanation of what happened when you attempted to install Windows 10?

What did you use to install Windows 10? A DVD or USB flash drive. Did you use the Media Creation Tool for Windows 10? Was the media for Windows 10 created recently?

You should not use Legacy if UEFI is available. Even Windows 7 64bit can boot from a GPT disk required for booting from a UEFI enabled computer.

Acer's boot menu is available on some computer's by tapping F12 at boot. This is enabled in your BIOS/UEFI settings.

https://www.youtube.com/watch?v=KycrBtjuJHc

download the windows 10 iso and install it.  windows 10 will pick up the licensing and it will install without having to install windows 7 first.