I had to go fix my parents' printer a few days ago. After a while, I figured out that Comcast had upgraded their router firmware and while doing that, they "helpfully" turned off the 2.4GHz Wi-Fi band without telling anyone. And their printer (like some models of Roku) only works on 2.4Ghz. So, that's one possibility.
Of course, I'm just guessing that when you said "not work" you meant it can't connect to your router. If I guessed wrong, maybe more details would help.
