どういたしまして。=You're welcome. (dou itashimashite.) いいえ。=No problem/Don't mention it. (iie.)

I'll write some variations, I often say. Hope you find the appropriate one for your feeling. いいえ、どういたしまして。iie dou itashimashite. : You're welcome. / My pleasure. (+ don't mention it / No problems. because of "いいえ”） いえ、いえ。ie ie. : no, no. / no problems. こちらこそ。kochira koso. : no, I should thank you. / thank you, too.

I normally say just いいえ(iie.)

どういたしまして=You're welcome or Nothing much.