I accidentally pressed dismiss instead of just ending the conversation with my dog and now he went off to some place. I really would like to have my dog back. If someone knows how to recover him that would be awesome. I know the game is new, but if you find out please let me know.

Dogmeat should be in Sanctuary if you dismissed him. Just go back to your old house, where you first ran into Codsworth. Dogmeat should be nearby.