Before trying any troubleshooting, we recommend you try resetting the remote control:

Remove the batteries from the remote control.
Note: Opening the battery compartment cover will vary, depending on the type of remote control. For details, refer to your TV manual.
On the remote control, press the Power button for three seconds.
Reinsert the batteries, making sure they are inserted with the correct polarity (-/+), then see if the issue is resolved.
If the issue is not resolved, remove the batteries again and leave them out for approximately 1 minute. Then, reinsert the batteries.