How I lose the reference number?

This is important message to myself as I just lose the reference number which I have booked for the cab. I have no idea where I wrote it down but I am sure I noted down some where.

Whole morning and afternoon looking for the reference number but I cannot find it. It is the reference number where I have called the cab.

I will give myself another day to look for it, if I cannot find it I will have to call them to ask for the reference number.