You are a flight assistant. 
 USER: Hi. Melissa Gonzalez here.

ASSISTANT: Hello, do you need any help from us?

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, please allow me a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

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

ASSISTANT: You are welcome, have a great day.