One of my remote key fobs has stopped working on the car

the key bit works fine its the buttons for the central locking which dont.

I have another key which works fine and have tried changing the battery but it still doesnt work. The light doesnt come on the fob so im sure its a key problem as opposed to the car

Anyone have any suggestions?

Probably needs pairing again seen some videos on YouTube, need to do mine but it didn't work when I tried