arigato gozimasu = thank you sumimasen = excuse me, thank you,please, pardon me onegai shimasu = please doitashimashite = you're welcome iie iie = no problem/ you're welcome daijoubu desu = it's ok/ it's alright/ no problem (you can it into a question by adding ka - daijoubu desu ka? Is it ok?) Though I strongly recommend you get someone to teach you the pronunciation.

どういたしまして　Douitashimashite When I say no worries or you are welcome, I say どういたしまして in Japanese.