If your Roku remote isn't working, first check the batteries and replace them if necessary. Make sure the remote has a direct line-of-sight to the Roku device, and try restarting the Roku player by unplugging it, waiting for a few seconds, and plugging it back in. If you're using a Wi-Fi remote, you can try re-pairing it by pressing and holding the pairing button for a few seconds, but this won't work for IR remotes.