If you're talking about the remote you may be out of luck.
Insignia is Best Buy's house brand and it is fairly new to the market and it could be that the code for your TV just does not exist in the remote's code library especially if it an older remote.
Your best option is probably checking to see if the cable company has a different type of remote that you could try. The remote companies update their code librbaries periodically so a newer model or a newer version of the current remote may work.