See if anything on this linked article helps (follow the instructions fully).
Otherwise try a full factory reset on your NowTV Stick (assuming you are using a NowTV Stick) by holding in the reset button on the Stick for about 15 seconds.
Usually the trouble shooting help article or a full factory reset will fix most NowTV smart remote problems.
You may have a faulty remote or the wifi between the remote and stick is not great.
Have you another television to test the Stick and remote on ?
If you are still not having any joy, then see if NowTV live chat can assist you further (use the green chat online button from this link page below to get in touch with NowTV).