You can give these troubleshooting steps a shot
Reset the remote.
Remove the batteries, and then press the Power button for eight seconds to reset the remote. Then, reinsert the batteries and try to use the remote again. Check out the user manual if you need help accessing the battery compartment.
Check if the remote is sending an IR signal.
Take either a digital camera or use the camera on your phone or tablet. Point the remote at the camera, and then press and hold the Power button on the remote. As you hold the button down, look at the camera's screen. If the remote is sending an IR signal, you will see a colored light coming from the remote control.
If you have a Smart Remote, try to pair it with the TV.
If the remote will not pair: