My remote has been deleted how do I get it back

For the software remote on iPhone, if it no longer has an icon in Control Center, then see iPhone: Settings﹥Control Center﹥ to move the Apple TV Remote widget from the inactive set to the active set, using the green (+) button.

Probably needs to be paired to the device again. This might help: If your Siri Remote or Apple TV Remote isn't working - Apple Support