Problems installing Windows 10 Home on PC with Windows 10 pro

I have really messed up. My computer was upgraded to a WD Blue SSD about a year ago. Tech guy installed Windows Pro but did not provide a product key and now MS wants a valid product key. Picked up an official Windows 10 Home USB key and went to install it. Would not install on the hard drive(s). apparently they are not formatted correctly. Accidentally hit “Reformat” on the same page of the installation and now I don’t have the old Windows 10 Pro and am unable to install Windows 10 Home. Please help.

Contact Microsoft Support. This is not a WD issue. MS Support helped me with Win 1o and they can help you.