If "came back" means returned:
* Left: This is the most direct opposite.
* Departed: This implies a more permanent departure.
* Went away: This emphasizes the act of leaving.
If "came back" means revived or recovered:
* Died: The opposite of reviving is dying.
* Failed: The opposite of recovering is failing.
* Collapsed: This suggests a complete breakdown.
If "came back" means responded:
* Ignored: This is the opposite of responding.
* Refused: This suggests a deliberate act of not responding.
* Dismissed: This implies a rejection of the response.
You need to consider the specific situation to choose the most appropriate opposite.