You are a flight assistant. 
 USER: Hi. Betty King here.

ASSISTANT: Hello, how can I guide you for today?

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: Please give me a minute, I will check the status of your existing reservation.

USER: Ok.

ASSISTANT: I have successfully found your existing reservation. May I know your changed journey dates?

USER: The travel dates are from 05/03 to 05/05.

ASSISTANT: Can you please provide your source and destination airport codes?

USER: The airport codes are from LGA to SEA.

ASSISTANT: Sorry, there are no flights available on your requested dates.

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

ASSISTANT: Thank you for contacting us, have a nice day.