It means you lost your remote and buy a replacement. If you current air-conditioner doesn't come up with remote, it won't work.
But you can install one switch at the power socket (done by electric engineer) and use the remote to turn it on/off. I installed one before on the old air-conditioner which requires manual switch. But shortly after that, the air-conditioner broke down and need to buy a new one. Now almost all air-conditioner comes with remote control.