You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Ryan Walker.

ASSISTANT: How may I help you?

USER: I want to change my existing reservation, can you help me?

ASSISTANT: Sure, I am here to help you. Let me check your reservation status in our database. Ryan, sorry for inconvenience no reservation is found on your name in our database.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Your are welcome.