From Longman Dictionary of Contemporary Englishfind your tonguefind your tongueinformalTALK TO somebody to say something after you have been silent for a time because you were afraid or shy Polly found her tongue at last and told them about the attack. → tongue
Examples from the Corpus
find your tongue• She moved her mouth about a bit to see if she could find her tongue.• When she came into the room, I had trouble finding my tongue. 