Ensure your remote has fresh batteries. Dead or weak batteries are often the cause.
Try resetting your remote by removing the batteries, pressing every button twice, then reinserting the batteries.
Clean the buttons and the front of your remote. Dirt can interfere with functionality.
Ensure there are no obstructions between the remote and the TV. Other electronics can also cause interference.
If all else fails, a universal remote may be a good alternative. They are programmed to work with various TV brands.