[Zahid_Hossain01]

Cortana on Windows Phone 10 Mobile used to have a feature for automatic text replies during a range of quiet hours that you can set in the Notebook. Cortana has been updated now and the Notebook looks completely different. I can no longer find the old settings for quiet hours.

[akhinch]

Are you able to access in it the action center?

[spicypadthai]

I'm not sure if this is what you're asking but there's still an option for a text auto reply to non-breakthrough list contacts: Cortana > Notebook > Quiet Hours, scroll to the bottom and in the Texts area there's an option for "Send a text to contracts who aren't allowed through saying tham I'm busy right now". If you check it, you'll see the reply, but there's only 1 and it can't be customized.

[BMachineW]

I'm having the same problem since I updated my phone a few days ago, I haven't found it yet, I'm still looking.

Found already!

Press and HOLD the quiet hours button in notifications bar to bring up the full menu of options.