Check the remote control for its infra-red emission. Check it with fresh batteries. Check by pressing all the buttons on it; and see whether all of it generates infrared signal while pressing. If it is found OK, check and replace the infrared sensor inside the TV. If you wish to get some details; check the site linked here. It has details about how to check a remote control; by one among the post. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/
If the remote control is found OK; check and replace the infra-red sensor inside the TV. Contact any service technician.
If the remote control is found OK; check it with set it up to an other set-up code said for your TV. If you wish to get more details; check the sites linked here. It has set-up code list &
set-up procedure to many popular brand remote controls. Common set-up codes to check with TVs and other devices are given, in the order of the "device's brand name list" in alphabetical order. Pull up older posts. Surf the site with patience. Surf the sites by type in the brand name to your set, in its search box.