To add to the other answers (which are correct), if you were offering someone a serving of yoghurt, you could say “Would you like a yoghurt?” The meaning is “a serving / bowl / bottle etc. of yoghurt (most likely a single-serving package of yoghurt). Note the use of “would” instead of “do”. EDIT: Gary caught a stray letter that somehow slipped in.... Lol.

right, It must be "Do you like yogurt?"

Yogurt is not countable, so the correct thing to say is "Do you like yogurt?"

A yogurt= 1 yogurt.