I got new wifi and I have no Roku remote

You didn't state your Roku model number. If your new router is using the same SSID and password as your old router, then the Roku should reconnect to the WiFi without an issue. But if the SSID and/or password is different, you must have a remote to reconnect the Roku to the WiFi. You have no other option. This of course doesn't apply if your Roku has an wired Ethernet connection. In that case your Roku should be visible in your Roku app on your phone, unless there's a security setting in your new router that is blocking connected devices from seeing other connected devices on your network. You'd have to check the router settings for that.

As long as your Roku is NOT a Roku Stick (the kind that connects directly to a TV without a cable), you can get an inexpensive universal IR remote to control the Roku. I see them available in local stores that sell remotes for less than $10. Just make sure they list Roku as a supported device. If you do have a Roku Stick, you MUST have an official Roku remote, as the Stick models are all WiFi Direct only for the remote. And if you have the old purple Roku Stick, you can't get a new remote at all, as that device is no longer supported by Roku.