If you have the NOW Stick then you need the NOW Smart Voice Remote which can be either all black, or have a touch of yellow or pink on some of the buttons.
Here's a picture of the black version.
Does your remote have a TV volume buttons on the side and a voice search button?
If you have accidentally bought the older NOW infra red remote for the NOW Black Boxes and it doesn't have the microphone voice search button & TV volume buttons on the side of the remote then you can possibly get a replacement directly from NOW live chat by clicking on the order remote button on this link (don't know if they currently have stock or not of the voice smart remote).
In the mean time you could use the free Roku Remote App on a smartphone or tablet that you can download from your mobile device Apps Store.
Thank-you for your reply. I have a Yellow Now TV Stick Model: 3801 I purchased 2 Different Remotes and I receive a Message on Now Tv Screen ' To Pair My Remote' But I'm unable to pair it up as there was no button in the back of the remote to do it.
If you have the correct NOW Smart Voice Remote has the picture that I previously posted there should be a small pair button underneath the battery cover on the inside of the remote.
Have a read of this.
DId you try NOW live chat by clicking on the buy remote green button from my first posted link ?
Before contacting NOW live chat, have you still got the original NOW remote that came supplied with the Stick ?
if so have you tried a full factory rest on the Stick by pressing the small reset button on the Stick for about 15 seconds when the Stick is powered on.
Then setup the Stick from scratch again making sure you use you existing NOW account details.
if the Stick then doesn't work with the original supplied remote, open the battery cover of the original Stick remote where there should be a remote model number (usually starts with RC).
if you have thrown out the original Stick remote, then jump over to NOW live chat.
Just seen your last post.
If you are going to give the free Roku Remote App a go on your smartphone or tablet then don't do the factory reset that i suggested.
Otherwise the Roku Remote App on your smartphone or tablet will not work when setting the Stick up from its default factory settings (where you need a suitable working NOW smart voice remote controller to initially set up the Stick after a factory reset).