come back vs unspeak

come back

verb
  • To retort. 

  • To return to one's possession, especially of memories. 

  • To return to a former state, usually a desirable one; to become fashionable once more. 

  • To return to a place. 

unspeak

verb
  • To retract what one has spoken, to unsay. 

How often have the words come back and unspeak occurred in a corpus of books? (source: Google Ngram Viewer )