Hi @Anonymous User
The Walking Dead S1 to S9 plus the first half of S10 left the NowTV service at the beginning of March if my memory serves me right.
i believe Amazon Prime Video may have S1 to S8 or S9 if you are a Prime subscriber.
I have no idea when they will be returning back on NowTV.
if you have a Twitter or Facebook account maybe ask NowTV over there where NowTV Staff seem to be more proactive, where the Community Forum is mainly used by customers.