Dear Mr. smith,
I am writing this letter to express my regret and sorrow with the failure to attend the admission interview being arranged on 15th, October.
I had faced the unavoidable event, and then I had missed your interview. I am a foreign student and I came here with my brother, and so the only relative that I have is him. Yesterday he got into the accident and brought to the emergency room of the Qurickland Hospital. He got into a life struggle for a while and now keep in ICU. I got so fretting by that condition and could not shaken it out.
I am sincerely sorry for being unable to come to your interview yesterday. I am aware of how much important was the interview as it decided my entrance to the Queen University. I would appreciate if you could reschedule our appointment to tomorrow or later tonight.
My brother is in critical condition now and therefore, could u please provide me with the information how long the interview is going to take and whether any exam during the interview. I would like to manage and prepare for it while taking care of my brother.
Please look into the matter at your earliest convenience. I look forward to hearing from you.
With respect,
Jennie. 
Dear Mr. smith,
I am writing this letter to express my regret and sorrow with the failure to attend the admission  
interview
  being arranged
 on 15th, October.
I had faced the unavoidable  
event
, and then I had missed your  
interview
.  
I
 am a foreign student and I came here with my brother, and  
so
 the  
only
 relative that I have is him. Yesterday he  
got
 into the accident and brought to the emergency room of the  
Qurickland
 Hospital. He  
got
 into a life struggle for a while and  
now
  keep
 in ICU. I  
got
  so
 fretting by that condition and could not shaken it out.
I am  
sincerely
 sorry for being unable to  
come
 to your  
interview
 yesterday.  
I
 am aware of how much  
important
 was the  
interview
 as it decided my entrance to the Queen University.  
I
 would appreciate if you could reschedule our appointment to tomorrow or later tonight.
My brother is in critical condition  
now
 and  
therefore
, could u  
please
 provide me with the information how long the  
interview
 is going to take and whether any exam during the  
interview
. I would like to manage and prepare for it while taking care of my brother. 
Please
 look into the matter at your earliest convenience. I look forward to hearing from you.
With respect,
Jennie.