

The search result should show up listed by number since the contact was deleted (definitely let us know in the comments if you experience otherwise). This search uses data that isn't purged very often (the spotlight cache), so the message may show up even if the text messages were deleted long ago. If you texted them, or they sent a text to you and can remember some words of note from the text conversation, you can try searching for that notable text in your iPhone search. If so, the call should appear listed by phone number. Try scrolling down through the recents, and see if your last phone call with them is in the history still. If you called them, or received a call from them in the past, you can open the "Phone" app and select "Recents" at the bottom.

Maybe it was an accident, or maybe you didn't think you needed to talk to this person again, but you deleted a phone number or contact from your iPhone, and now you need the number again! Let's go through some ways you can try to find that phone number.
