hacked pc

  1. Windows 10 free upgrade to win 10 now i have to use my win7

    hello, To cut it short my pc got hacked yesterday and had malware and other stuff on it so i had to act quick tried to clean install win 10 through usb but didnt work out well for me so i used my win 7 cd to format driver and install it. my question is will my product key work on win 7 after i...