You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Katherine Lopez here.

ASSISTANT: How can I assist you?

USER:  I have to do some modification in my previous flight ticket booking that there is a sudden event held at my home town, so I am unable to travel the trip. can you please help me out with changing of my reservation?

ASSISTANT: Sure Lopez, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say that, there is no reservation found on your name.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for approaching us.