[Q] Htc one problem topic

Hi everybody,
i have a Htc one M8. I accidentally deleted the OS from my phone. So I tried flashing a rom like Viperonem8 and I succesfully installed but I couldn't turn the wifi on so I deleted everything and tried a diferent one. I flashed the Skyfall rom bu I still can't turn the wifi on. I've read that i have to install the official firmware but how do I do that? My Htc is s-on.