J,
You probably caused your TV to go through an autoprogram sequence from its over-the-air input, and those three channels were the only ones broadcast in your area. I suggest you use the original remote to go the the TV's menu system. Find the autoprogram command, and ensure that Cable input is selected.

Hz,
I suggest you try a UEIC-type remote such as the OneForAll Cinema 7, or the Philips/Magnavox REM400. These remotes have a large code library. Check the return policy at the store and ensure you can return it if it doesn't work for you. Then, make sure you try all the codes listed for your device. The REM400 may have an even better chance of supporting your TV, being branded with the same name. These two remotes sell in the $25 range.