What is wrong when TV picture with no sound when attached to cable box using TV

sure..

try a different source connected to the same input jack on the television.
if there is no audio, its the television.

you could try a different input on the television to see if there is any audio.
perhaps using the RCA jacks for audio input will work.

you need to know if its the cable box or the television.
and the best way to test the television is to hookup something else with more than one method.
because maybe the cable input is broken but the television amplifier and speakers still work with the RCA audio input jacks.

probably a really good reason to hunt down an old VCR