Assuming you are now running Windows 7 Pro. Yes ?
Since you had Windows installed and activated, you have the Digital License kept in the server.
Digital License allows you to re-install the SAME edition of Windows 10any time you want and as often as you want.
Use this link blow :
https://www.microsoft.com/en-ca/software-download/windows10
Click the Update Now button.
You will be asked to enter product key. Just select the SKIP option or the "I do not have a product key" option and continue.
You can keep your files, settings and apps.
Activation will be automatic.