no worries

Short definition from Wiktionary

Interjection

1. 1
   A general injunction not to be concerned further with a subject: It does not bother me; I am not concerned.
2. 2
   A general injunction not to be concerned further with a subject: It was no problem; not at all; you're welcome.
3. 3
   A general injunction not to be concerned further with a subject: Do not worry, I will do it.