Can i say
"thank you for your pleasant answer"
First, please note my corrections above. It is important to capitalise the word "I" every time you write it, to start every sentence (including one in quotes) with a capital letter, and to end every sentence with one, appropriate punctuation mark.
Your sentence is grammatically correct but it's not very natural. We are more likely to refer to an answer as "helpful", "prompt" and other adjectives but "pleasant" is an unlikely one.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.