I have a 56in TV model #d56w20 after I took it into get the catv fixed on the back I can nolonger use any type of remote on it...

The problem might be 'mechanical'... The infrared remote receiver device may have been bent out of position during the repairs, and no longer aligns with the hole in the front that lets the IR signal in.

But I wouldn't recommend you try fixing it yourself. Best to take it back to where you had it repaired and make them fix it (free), since they caused the problem.

Daniel