This only applies if your Firestick remote looks like this one! This being the case, you have one of the first generation Firesticks.

From time to time your remote may stop responding, the first thing to check are the batteries - Firesticks seem to munch through batteries! Try some fresh batteries.

If this doesn't work, and this also applies if you've purchased a new remote for a lost one, you can pair or repair your remote using the following method:

Press and hold the Home key (looks like a house - centre button, top row) for 10 seconds or more until you get a message on screen saying the remote has paired.

You may have to try this more than once!! I recently did one and it took me 4 attempts!