Doctor...
How's everything going?（问候用语）
I am C's mother, and I am very anxious since I don't hear from C for several days. I don't know what hapens on him, could you please help me and try to contact with him? Please let him to call me if you get in touch with him.
Thanks so much
Looking forward to your early reply.（期待您的回复.）
署名
（最好把你的电话也给博士一下,邮件联系毕竟不是很方便的）