You can see your linked devices at https://my.roku.com Unfortunately, they don't show the model number (what's up with that, Roku?) which is much better than just the name that shows up since Roku has the annoying habit of reusing the same name over and over again for a totally different model.
If it's a box and not a stick, you may just want to get a cheap universal remote that supports Roku. You can find them at your local big box store or even a dollar store. You can also get an app for your phone to act as a remote. Just make sure you get the official Roku app and not some 3rd party app.