Hello,
i have an interview next week , and i want to write thank you letter, and i dono the address for the company? how can i ask for it professionally
I would sincerely advise you not to send them anything in writing prior to your interview. Your lack of punctuation, capitalisation, incorrect spelling etc. will almost certainly send you to the bottom of their list of potential employees. Besides, the appropriate thing to do if offered an interview is to simply turn up on time for it, dressed appropriately and ready to answer difficult questions.
Still, if you feel you must send them a sample of your written English, you ring the company, and say, "Could you help me, please? I have an interview with X next week, and I want to send a thank you note. However, I don't know the address to which I shoud send it. Would you be able to tell me, please?"
Or, if you need the address for the interview, as your topic line suggests, substitute "and I don't know the address at which the interview is to be held."