"than" cannot be used without another comparative word. Because of this, the meanings of your sentences are not clear. If you are talking about preferences, you can use "rather than" e.g "I want to play the piano rather than watch TV" or "I would rather play the piano than watch TV" You have two choices - they are both OK, but you prefer one of them. If you want to make a simple comparison between two things you would use "more than" e.g. "I like playing the piano more than watching TV." Comparisons need to be studied in detail and most grammar books and coursebooks have a unit which focuses on them. YuYechan was probably right and was trying to be helpful. In this context, a reply with "nope" seems rude and so I advise against it.

I was little bit confused, sorry but ı think michael's answer will be useful for all of use. Thank you for you ur attention

Do you mean 'than' or 'then'? You could have 'I would prefer to play piano than watch a movie' so you are making a choice, or 'I would like to play piano then watch a movie' so you do one thing and then next you do the other. 'Than' never starts sentences, but 'then' can start sentences e.g. 'I watched a movie. Then I played piano.'

Excuse me, what do you mean by saying: must I write a sentence after than? Can you make an example?

Nope, than can be used for comparisons but did you say to use the sentence should we use rather than?