1.Unfortunately,due to some unfortuseen business,i will be unable to keeb our appointment for tomorrow afternoon.
2.Would it be possible to arrange another time later in the week?
3.i'm afraid that I have to cancel our meeting on Wednesday, as something unexpected has come up.
4.You know we were going to meet next Friday? Well, I'm very sorry, but something urgent has come up.
5.I,m afraid that I,m not going to be able to meet you after all. Can we fix another time?