Apple TV 3rd Generation Issue with change of WIFI router

Hi All

I have the Apple TV 3rd generation and about 6 months ago my apple remote stopped working. So from then on I just used the remote app on my iphone. Recently I changed my wifi account and it has new wifi name and password. When I turn on the Apple TV it shows me two icons and one is settings. I am unable to use the remote app as the Apple Tv shows its offline. Which is understandable as it cannot connect to wifi. So I went and purchased a replacement Apple Tv remote thinking this would solve the problem, but it has not. The light on the box flashes when I click on the buttons on the remote but it cannot select anything on the screen. Has this happened to anyone else? Can you please help me get this resolved? How can I change the settings on the Apple TV? Is there anyway maybe I can reset the tv to factory settings to start the process again? I would be very grateful if I could get some help.😟