From old HDD to new HDD – activation!
Yes, you can replace the hard drive and reinstall 8.1 on your machine.
You can contact the Laptop/Computer Manufacturer and order Recovery Media from them for a tiny cost.
You can download and create your own Windows 8.1 Installation Media to reinstall the Operating Structure with..
“Create installation media for Windows 8.1”
“Download Windows 8.1”
A similar Discussion Group which may also assist you
“Create Installation Media for Windows 8.1”
In the first screen of this very easy wizard, you need to choose the following:
Language. English – en-us if you’re in the Amalgamate States.
Edition. Windows 8.1 (Core), Windows 8.1 N, Windows 8.1 Pro, Windows 8.1 Pro N, or Windows 8.1 Lone Language.
Architecture. 64-bit (x64 ) or 32-bit (x86).
“How to Create a Bootable USB or DVD with a Windows 8 or 8.1 ISO”