Roku will not accept my new Wi-Fi

In order to help, we can use some more information.

What model Roku do you have?  Both model name and model number would be helpful since Roku tends to repeat model names with new released models.  If you can see the on-screen menus, Settings > System > About will give you this information, otherwise it should be written on the unit somewhere.

Assuming you have other devices that DO connect to your router, it is helpful if you can tell us what channel number they are connecting to.