Junior college adjunct English instructor here – not in the same league as the miscreant in the OP, of course, but still …
I gotta’ go with Airman Doors’ reply. I’d issue semester grades based on the work completed up to the final.
And then I’d go shoot myself. :smack:
I would drop them - but give people the chance to take it next semester if they weren’t happy with their grades.
There are a few who will always have good grades. This won’t matter to them.
There are a few who started slowly but buckled down. They need a chance for a final.
There are some who will do poorly either way.
I’d let the average of the other grades stand as the student’s final grade … and, of course, never tell anybody I lost the finals at all, unless university procedure dictated that the students had to get them back. (It hasn’t at either of the two schools where I’ve taught, and I’ve hardly ever had students ask to see the final or go over their scores.)
If I were teaching at a place where it was standard procedure to return the exams, well, I guess I’d just have to tell the students that everybody performed so abysmally on the final that I decided to be very generous and pretend I never received them at all 
This kinda happened to us… we were due to take a paper, but in the final lecture of the module our Prof told us she’d given us totally wrong material, and that we’d not recognise anything on the exam paper. :smack:
We were simply told to go in “and try your best”. Great huh?
They then took into account our attendence at lectures, our participation in groupwork, the marks from our (ungraded) tutorial essays, and our essay mark, and gave us a revised total.
For me, it confirmed my policy of trying 100% in all tests - even the “ungraded” mid-term papers - if something happens like this, or if you are ill etc in the Finals, you have some ammunition to argue for a decent grade.
Amen to that. Plus, if a student says that her exam was lost by the TA or instructor, but cannot produce her electronic copy (per my policy of saving everything until grades are posted), there’s a less compelling case that the faculty lost the exam.
The worst exam screwup that happened during my time as a TA was having insufficient blank exams to pass out. The department printer (that is, the guy who’s job it was to print things for the department) would make N+2 copies of the exam for each TA to give to their section, where N was the number of students enrolled in that section. The two extra was supposed to cover the occasional printing mistake.
The problem I had was my section had 40 students, which was over the maximum of 32. Yes, the registrar had screwed up and over-enlisted my section. Eh, I could handle that many, no problem. Except the printer, who “knew” that no section could have more 32, only give me 34 exam copies. Naively, I didn’t count my copies before I went to the classroom (a good 15 minute walk from the department). While passing the exam out, I came up six short.
Two of the students were relieved, but the others were actually upset. I told them I couldn’t do anything about it immediately (since I had to proctor the rest of the class), so I wrote them each a slip stating they were present, but couldn’t take the exam because of an exam shortage. :smack:
After the exam period, I went to the professor (I think a few of the student tagged along) and told him the situation. He agreed I handled it well and was mightily pissed at the printer. We went to the printer and I got to watch his rear get chewed out about paying attention to details like “actual number of students” versus some “theoretical maximum”.
The students got to take the exam at a time of their choosing. I think the department head eventually went to the registrar to make sure maximum actually meant maximum.
I’ll vote with the majority here…offer to keep the grades or retake. However, when the retesters came in, imagine their glee when they see that it’s the exact same exam over again. They did restudy, especially the questions they weren’t sure of the first time, right?