There’s no such thing as a ‘USB NowTV‘. They are powered over USB, but connect by HDMI.
is it a Stick, plugs directly into an HDMI port on the TV? Or a box - white or black, small and round, or squarish and flat?
And they all come with a NowTV remote, so what do you mean by ‘make of remote’?
Are you trying to use a universal remote with it? If so, you may have more luck talking to the makers of that.
Did it ever work? Or is it that it worked before, and now doesn’t?
There are two functional area on the remote; the On/Off button at the top plus the up/down volume buttons on the right hand side; and everything else.
On/Off/volume+- work your TV by infra-red, and are set up separately from pairing the remote with the Stick by pressing the pairing button that is under the battery cover.
Did you set both aspects up originally? Which aspect(s) don’t work now? Have you tried new batteries?
Read the Help on pairing, and maybe try it again if it’s not the batteries worn out that is the problem. One or more of the three articles here may be relevant:-