'Google Now' and 'Google Assistant' Gone after Phone Reset


I bought my phone in September 2016. The phone had Marshmallow when it arrived.

I got the Nougat update some time in January and since then my phone had Google-Now and the Assistant when I swipped the home-screen towards the right.

Recently my phone had an issue due to which the service centre had to reset it to factory settings. The phone, now, still has Nougat but no 'Google-Now' and no 'Google-Assistant' either. I basically cant swipe right on main home screen and saying 'Ok Google' just opens up Google Search and not the assistant.

I go to Settings -> Google and I see only 'Search' not 'Search and Now' and no assistant option.

Please help. I need the assistant and Google Now back.