There was patent problem that was taken care of by software update, outcome not as many tv codes available as before. Curtis is made by other tv manufacturers, so they could still be a brand whose code works on yours, but just isn't listed under Curtis. You are the only one to find out which other brands work your particular model. I suggest getting a cheap UEI, the patent owner, universal remote like the Onn 6 universal remote cheap on ebay. It has code search feature, and a way to blink back the search result. You would take that code and go through tv brands in the manual that share those same codes. The brands you come across, try those brands in the Roku remote.
Onn 6 universal remote for sale | eBay
Knowing these brands will help in the future when programming a remote for your tv.
Edmund
Roku Community Streaming Expert
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