Dear Lily,
I so sorry that I have broken our appointment.I am here writing to apologize for falling to keep the appointment.The reason is that my mother was ill on sunday.So I have to take care of my mother on that day.That is why I didn't come to meet you on sunday.I so sorry.Shall we meet on next sunday If it is convenient for you,please call me at 256890.
I am looking forward to hear from you soon.
your surely,
Mary