Remote controlled gas fires use batteries in the hand held remote control and also in the product if it is not mains powered. If the batteries are low the appliance may not light, in this instance the batteries will need to be replaced using good quality Alkaline batteries (do not use low energy batteries).
Please refer to your installation instructions for the amount and location of your batteries. If your gas fire still fails to light, please remove the batteries from your gas product for 30 minutes, then replace and retry.