I missed 3 of my semester exams back in 5th semester due to an unavoidable reason so, I am qualifies enough to answer this question.
If your reason for missing the semester exams is genuine enough that you can write an email to the COE addressing your problem. Make sure you drop at least 2 to 3 mails.
At college, you can talk to your class incharge and HOD and put forward your problem and reason for missing the exam.
Write a letter to the COE and hand it over in the office by hand.
If your reason is genuine enough that you will appear for your exams with during the next semester as something called “First Appearance” in which case you do not have an arrear and your marketeers for both the semesters will be issued together. Else you will have an arrear and appear for it in the next semester.
Whatever maybe the case, never miss more than 3 exams or you will have an year back, genuine reason or not. Period.