Welcome to the forum.
You can buy a replacement remote from the Sky Store. The link is here
Although if you regularly have a cinema or entertainment pass, you'll probably find buying a new black NOW TV box with a bundle of passes works out cheaper than buying a new remote once you factor in the value of the passes you get with it.
Whilst you are sorting your remote out, if you have an Android or Apple phone/tablet you could download the official Roku app from the relevant App Store and use that to control your NOW TV box.
@Charlleegilbert The Roku app is only adviced to be a temporary solution. You are better off purchasing a new remote using Andy's link just above your post. 🙂
They aren't expensive. 😉
If your box is white, the black remote will work with it.
Just-so-you-know... Retailers such as Currys, Argos and Amazon regularly offer the newer 'black' NOW TV boxes bundled together with multiple-month Movie or Entertainment voucher code passes, which often works out costing a lot less than the equivalent multiple monthly NOW TV subscription. I'm currently using the newest (and much faster) 'smart' NOW TV box which I managed to purchase on a similar offer.
In many cases this means that your new box ends up costing you nothing
@Philadelphia Welcome to the forum. If you have an iPhone try the NOW TV app on there, it can act as a remote for your box. If you have an Android phone you can try the Roku remote app instead.
Not sure why your box is behaving like that, but try a forced software update to see if it helps (assuming the remote will work to let you do it).
Press Home on the remote to take you to the home screen. Then do the following sequence on your remote quickly and smoothly
Home (x5) FF (x3) REW (x2)
If done correctly a Secret Screen will appear (if it doesn't, press Home to go back to the start and then try again). Choose Update software and allow it to run (even if it reports the same version as you already have).