How to find a lost phone number?

"Lost number: Trying to find phone number"

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Finding a Phone Number:

Phone Number for What?

So...

1. use the search bar in your Contacts app
2. view the Call History
3. look on other devices
4. log into your carriers site (logging in, myself, I can see a call history log going 30 days back)

What phone number are you looking for? We need more information before we can assist.