It looks like you may have a stick. If so, you'll need one of the Voice Remote models. The Voice Remote is $20, and the Voice Remote Pro is $30.
They are available online, or from Walmart, Best Buy, Target, and other retailers.
These remotes will work on any recent (since 2013) Roku device, whether box or stick. They also work with Roku TVs.
If you don't have a stick, nor a Roku TV, the Roku Simple Remote ($15) will work. It's IR only. Or, you could find a cheap universal IR remote from Family Dollar, Walmart, CVS, Walgreens, or other such places, often under $10. Just make sure the packaging says it supports Roku.
DBDukes Roku Community Streaming Expert Note: I am not a Roku employee.
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