Windows 7 Restoring windows 7

Hi guys.

I have a Sony vaio that has recently been wiped unfortunately been hacked again for the second time damn neighbors.

Anyway I need to clean reinstall it all.

Apparently I need a product key.

I just had it repaired and the guy that repaired it upgraded it and didn’t give me the key and when I look under my computer it looks invalid.

So my question is how do I restore it now.

I need to use a usb stick to do this and I need know the a step by step process of how to do it.

If I can’t restore it back to windows 7 can I put it back to vista I have that product key on a stick on the bottom of the laptop.

I also need to know how to turn off any access they could make remotely to my laptop like remote administrative Remote Desktop or like maybe a vpn site to site connection. I want my laptop to be completely isolated however use the internet.

On the router they have set up a smb server with file sharing. How do I stop getting hacked.

It’s costing me 50 pound a laptop it’s ridicolous