My TV remote stopped working, The red light goes on still when i press a on, why isn't it working?

My TV remote used to work but it has stopped lately, it doesn't sound broken and i haven't dropped it or anything, and the red like on the remote goes on when i press a on, I have pressed the TV on on it, and the batteries are brand new. I even tried unplugging the TV to restart it but nothing. its a HITACHI MTS and it only goes up to channel 38 when you press channel on the tv.