How to reactivate Google Assistant after deactivating by changing Language?

I had got Google Assistant for my Android device. However, I prefered Now On Tap for few features like the ones mentioned [here] and deactivated Assistant by changing the language settings as mentioned [here]. But I was wondering how do I reactivate the Google Assitant, I tried changing back the language to English(US) in Settings -> Google-> Search -> Search Language but to no avail. How do I get back the assistant if I ever plan on using it?