Batteries: obvious, but sometimes we forget. Replace those batteries and see if it comes back to life.Make sure the batteries are in properly and that there is no lint or dirt in the battery compartment.
Obstructed Signal: If there are obstacles between the remote and the TV, the signal may be failing. Clear the path and try again.
Incorrect settings: Sometimes the remote gets out of configuration. Consult the manual to reprogram it with the correct codes.
Infrared problems: If the infrared sensor on the TV or remote is dirty, clean it. Sometimes a simple wipe will work wonders.
Electronic problems: If all else fails, there could be an electronic problem. Try resetting the TV or seek service assistance.
Expert tip: Sometimes the inside of the remote control gets dirty, specifically what can cause some remote buttons not to work while others do is a buildup of grease between the button and the electronic board. Our skin contains a small layer of grease, and sometimes we use the remote control with leftover food or dirt, and little by little that grease gets inside the TV remote control.
To fix this, you will need to open the remote control. Normally, inside the battery compartment, there is a screw that you can remove to open the remote control.
When you open the remote control, you will see two parts: the rubber that forms the keys and the electronic board. Remove the rubber and carefully wash it with soap and water. Be sure to dry this rubber completely before placing it back on the board. Alternatively, you can wipe the electronic board with dry paper to remove dirt and grease.
Reassemble the remote control and insert the batteries. Check if those buttons that did not work before are working now.
There are mobile apps that act as remote controls for TVs and other appliances.
If your cell phone has infrared you can use this feature using a universal application that works for all devices that work with infrared, otherwise there are specific applications for each brand that make use of the Wi-Fi connection to communicate with the TV and send the signal with the instructions to change channel, change volume, etc.
Apps that work with infrared:
Apps that work via Wi-Fi: