The only thing I can think of is a recent problem created by some internet services updating the settings on their provided router equipment. This has been reported recently with Xfinity and Cox, but there may be others.
This update changed the wifi security setting in the router from b/g/n to g/n. For affected users this resulted in failure to connect. I've not heard of this being reported as a password error, but I suppose different routers might respond with different error messages. I also don't recall having seen this reported for Roku TVs, only separate Roku devices.
I fear this may be a long shot, but if this indeed is the problem the solution is to change the router's security setting back to b/g/n. If you don't have access to your provider-supplied router's configuration you may have to request your provider do this for you.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X