Upvote:3
You should go to the Cebu Pacific Air office in your city with your ID. Do not go to a travel agent (unless you bought your ticket from them) or bank. If you don't know where their office is, there is one in the airport if they fly there.
When you come to the office, you show them your ID and tell them the booking information you know (origin, departure, date), tell them you never received your booking and ask them to look it up for you.